This Fruity Pebbles Protein Loaf Cake is soft, colorful, and packed with the sweet cereal flavor I remember from Saturday mornings as a kid.
I made it with zero-sugar yellow cake mix, vanilla protein powder, Greek yogurt, sugar-free Jello mix, and real Fruity Pebbles. It tastes like a funfetti-style loaf cake with the fruity flavor of the cereal mixed throughout.
The best part is that you do not have to make a cake completely from scratch. The boxed cake mix handles most of the structure, while the protein powder and Greek yogurt turn it into a more filling breakfast, snack, or dessert.
When divided into 10 slices, each piece has approximately 235 calories and 15 grams of protein.
Try These Next
If you love turning nostalgic desserts into high-protein recipes, try my Fruity Pebbles Protein Cake Pops (High Protein) next.
For another easy loaf cake, my High Protein Espresso Loaf Cake has a soft coffee-flavored crumb and works especially well for breakfast or meal prep.
Why You'll Love This Recipe
- Each slice has approximately 15 grams of protein.
- It starts with boxed cake mix, so the batter is quick and easy.
- Greek yogurt and Jello mix help keep the loaf soft.
- Real Fruity Pebbles add cereal flavor and color throughout.
- It works as breakfast, a snack, or dessert.
- The loaf can be sliced and stored for meal prep.
Ingredients
See the recipe card at the bottom of the post for the complete measurements.
- Zero-sugar yellow cake mix
- Vanilla protein powder
- Sugar-free Orange Jello mix
- Eggs
- Skim milk
- Nonfat Greek yogurt
- Fruity Pebbles cereal
- Optional protein glaze
Ingredient Notes
Zero-Sugar Yellow Cake Mix
The boxed cake mix keeps this recipe simple and gives the loaf its basic cake structure.
I used Pillsbury Zero Sugar Yellow Cake Mix. You can use another yellow or vanilla cake mix, but the calories, sugar, and final texture may change.
Cake mixes can also come in slightly different package sizes. If you use another brand, watch the consistency of the batter instead of automatically adding more liquid.
Vanilla Protein Powder
Vanilla protein powder works well because it increases the protein without covering up the Fruity Pebbles flavor.
Whey protein can still work, but different powders absorb different amounts of liquid. Your loaf may be slightly firmer, and you may need an additional tablespoon or two of milk.
Greek Yogurt
Greek yogurt adds moisture and protein without needing oil or melted butter.
I used nonfat Greek yogurt, but low-fat Greek yogurt will also work. Vanilla Greek yogurt can make the loaf slightly sweeter.
Fruity Pebbles
Fruity Pebbles give the loaf its color and recognizable fruity cereal flavor.
The cereal mixed inside the batter softens as the loaf bakes. The cereal sprinkled over the top stays more visible, although it will also soften during storage.
For a stronger cereal flavor, you can soak Fruity Pebbles in the measured milk before making the batter. Strain out the soggy cereal and use the flavored cereal milk in the recipe.
How Do You Turn Boxed Cake Mix Into a Protein Cake?
Adding protein powder to boxed cake mix is easy, but you cannot just stir in a large amount of powder and bake it exactly as directed on the box.
Protein powder absorbs moisture and changes the texture of the batter. Without additional moisture, the cake can become dry, dense, or rubbery.
In this recipe, the Greek yogurt, eggs, milk, and Jello mix help balance the added protein powder. The cake mix still provides the flour, leavening, sweetness, and most of the structure.
The finished batter should be thick but spreadable. It should not look like dough, but it should also not be as thin as pancake batter.
What Happens When You Add Protein Powder to Cake Mix?
Protein powder makes the batter thicker because it absorbs some of the liquid.
It can also make a cake firmer as it bakes. That is why protein cake recipes generally need ingredients that provide additional moisture, such as Greek yogurt, cottage cheese, applesauce, pumpkin, milk, or Jello mix.
The type of protein powder matters too. Whey, casein, plant protein, and protein blends all behave differently in baked recipes.
For this loaf, I prefer a vanilla whey and casein blend because it gives the cake more structure without making it as dry as some whey-only powders.
Fruity Pebbles Fluffy Yogurt Frosting
Instead of a standard powdered sugar glaze, I topped this loaf with the same fluffy yogurt mixture I use for my Fruity Pebbles Fluffy Yogurt.
The frosting is made by whipping cold nonfat Greek yogurt with zero-sugar white chocolate pudding mix and vanilla protein powder. It becomes thick, light, and almost mousse-like without using butter or powdered sugar.
Once the mixture is fluffy, I fold in Fruity Pebbles and spread it over the completely cooled loaf. The creamy white chocolate yogurt topping works well with the sweet cereal flavor while adding even more protein to the finished recipe.
This is a softer frosting than traditional buttercream, so the frosted loaf needs to be stored in the refrigerator. Add a final sprinkle of Fruity Pebbles immediately before serving because the cereal gradually softens after it touches the yogurt.
Equipment
9×5-Inch Loaf Pan
Use a standard 9×5-inch loaf pan.
A smaller pan will create a deeper loaf that takes longer to bake. A larger pan will make the loaf flatter and may reduce the baking time.
I prefer a light-colored metal pan because very dark pans can brown the outside before the center is fully cooked.
Large Mixing Bowl
Use a bowl large enough to mix the cake batter without spilling the dry ingredients over the sides.
Whisk or Electric Hand Mixer
A whisk works for combining the dry ingredients. An electric mixer can make it easier to blend the thick batter after the eggs, yogurt, and milk are added.
Mix only until smooth. Overmixing can make the finished crumb firmer.
Silicone Spatula
Use a silicone spatula to fold in the Fruity Pebbles without crushing all of the cereal pieces.
Parchment Paper
Lining the pan with parchment paper makes it much easier to remove the loaf after it cools.
Leave a little parchment hanging over the long sides of the pan to create handles.
How to Make Fruity Pebbles Protein Loaf Cake
1. Prepare the Pan
Preheat the oven to 350°F.
Grease a 9×5-inch loaf pan or line it with parchment paper.
Press the parchment into the corners of the pan so the batter spreads into an even loaf shape.
2. Combine the Dry Ingredients
Add the zero-sugar cake mix, vanilla protein powder, and sugar-free Jello mix to a large mixing bowl.
Whisk until everything is evenly combined.
Breaking apart the protein powder clumps before adding the wet ingredients makes it much easier to create a smooth batter.
3. Add the Wet Ingredients
Add the eggs, skim milk, and Greek yogurt.
Mix until the batter is smooth and no dry pockets remain. The batter should be thick but easy to spread with a spatula.
If the batter is too thick to mix, add skim milk 1 tablespoon at a time.
Do not add too much milk at once. A thin batter may take much longer to set in the center.
4. Fold in the Cereal
Add 1 cup of Fruity Pebbles to the batter.
Use a silicone spatula to gently fold the cereal in until it is evenly distributed.
Stop folding as soon as the cereal is mixed in. Crushing or overmixing it can muddy the colors in the batter.
5. Fill the Loaf Pan
Transfer the batter to the prepared loaf pan.
Spread it into the corners and smooth the surface with a spatula.
6. Add the Cereal Topping
Sprinkle the remaining ½ cup of Fruity Pebbles evenly over the top.
Press the cereal very lightly into the batter so it stays attached after baking.
7. Bake
Bake for 50 to 60 minutes.
Begin checking the center around the 50-minute mark. A toothpick inserted into the thickest part should come out clean or with a few moist crumbs.
If the top begins browning before the middle is finished, cover the pan loosely with aluminum foil.
Every oven is different. Use the toothpick test instead of relying only on the baking time.
8. Cool the Loaf
Allow the loaf to cool in the pan for approximately 15 minutes.
Lift it from the pan and transfer it to a wire rack. Let it cool completely before slicing or glazing.
The center continues setting as the loaf cools. Slicing it while hot can make a fully baked loaf look gummy or underdone.
9. Add the Fruity Pebbles Fluffy Yogurt Topping
Add the cold nonfat Greek yogurt, zero-sugar white chocolate pudding mix, and vanilla protein powder to a medium mixing bowl.
Whip with a hand whisk or electric hand mixer for 60 to 90 seconds, or until the mixture is smooth, thick, and fluffy. Gently fold in the Fruity Pebbles with a silicone spatula.
Spread the fluffy yogurt topping evenly over the completely cooled loaf. Finish with additional Fruity Pebbles right before serving for the best color and crunch.
Expert Tips
Measure the Protein Powder Accurately
Protein powder is one of the easiest ingredients to overmeasure.
Scoops vary between brands, and packing powder into a measuring cup can add much more than the recipe needs. Use the listed gram measurement whenever possible.
Do Not Automatically Add Extra Milk
The thickness of Greek yogurt and the absorbency of protein powder vary.
Mix the batter first, then decide whether it needs more milk. It should be thick but still spread easily across the pan.
Fold the Cereal in Last
Fruity Pebbles soften quickly when they touch liquid.
Folding them in at the end prevents them from sitting in the wet batter longer than necessary.
Protect the Top With Foil
The cereal on top can brown before the center finishes baking.
Once the loaf has enough color, loosely tent it with foil and continue baking until the middle is set.
Cool Before Slicing
I would not skip the cooling time.
The loaf is still setting when it comes out of the oven. Cutting it too early can compress the center and make the slices fall apart.
Wait to Add the Glaze
The loaf must be completely cool before you glaze it.
If it is still warm, the glaze will melt into the cake instead of staying thick on top.
Variations
Fruity Pebbles Cereal Milk Loaf
Soak Fruity Pebbles in the measured milk for about 20 minutes.
Strain out the softened cereal and use the flavored milk in the batter. Fold fresh cereal into the batter as directed.
Birthday Cake Protein Loaf
Add rainbow sprinkles along with the Fruity Pebbles for more of a birthday cake flavor.
Use jimmies instead of nonpareils because nonpareils are more likely to bleed into the batter.
Cocoa Pebbles Protein Loaf
Replace the Fruity Pebbles with Cocoa Pebbles and use chocolate protein powder or chocolate pudding mix.
This will create a completely different loaf, but the same basic cake-mix method should work.
White Chocolate Fruity Pebbles Loaf
Use sugar-free white chocolate pudding mix and add a small amount of melted white chocolate to the glaze.
Unglazed Breakfast Loaf
Leave off the glaze for a less-sweet version that is easier to package for breakfast or meal prep.
Substitutions
| Component | Swap Options |
|---|---|
| Zero-sugar yellow cake mix | Regular yellow cake mix, vanilla cake mix, or white cake mix |
| Vanilla protein powder | Whey and casein blend, whey protein, or another baking-friendly vanilla protein |
| Nonfat Greek yogurt | Low-fat Greek yogurt, plain yogurt, or vanilla Greek yogurt |
| Skim milk | Almond milk, 1% milk, 2% milk, or another milk of choice |
| Sugar-free Jello mix | Strawberry or Raspberry Jello mix |
| Fruity Pebbles | Cocoa Pebbles or another crisp rice cereal |
| Optional glaze | Powdered sugar glaze, melted white chocolate, or no glaze |
Storage
Refrigerator
Store the Fruity Pebbles protein loaf in an airtight container in the refrigerator for up to 5 days.
The cake stays soft, but the cereal topping will gradually lose some of its crunch.
Freezer
Let the loaf cool completely before freezing.
Cut it into individual slices and wrap each slice tightly. Place the wrapped pieces in a freezer-safe bag or container and freeze for up to 1 month.
Thaw the slices overnight in the refrigerator or leave them at room temperature until softened.
Frequently Asked Questions
How Do You Make Fruity Pebbles With Protein?
One of the easiest ways is to combine Fruity Pebbles with protein powder in a baked recipe like this loaf.
The cake mix provides the base, while vanilla protein powder, eggs, and Greek yogurt increase the protein. Fruity Pebbles are folded into the batter to provide the cereal flavor.
You can also add protein to Fruity Pebbles by serving the cereal with a protein shake, high-protein milk, or Greek yogurt.
How Do You Make a Fruity Pebbles Cake With Cake Mix?
Start with yellow, vanilla, or white cake mix and prepare a batter using the ingredients listed in the recipe.
Fold the Fruity Pebbles into the finished batter instead of beating them in with a mixer. Transfer the batter to the pan, add more cereal on top, and bake until the center is set.
Can You Add Protein Powder to Cake Mix?
Yes.
Protein powder can be added to cake mix, but it absorbs liquid and changes the texture. The recipe needs enough eggs, milk, yogurt, or another moist ingredient to balance it.
Adding protein powder without adjusting the wet ingredients can produce a dry or dense cake.
How Much Protein Powder Should You Add to Cake Mix?
Use the amount tested in the recipe rather than applying one ratio to every box of cake mix.
Protein powders behave differently, and cake-mix packages are not always the same size. Adding more protein powder does not automatically make the recipe better. Too much can make the loaf dry, heavy, or rubbery.
What Protein Powder Is Best for Baking Cake?
I prefer a whey and casein blend for cakes and loaf recipes.
Casein absorbs moisture and gives the batter structure, while whey helps the cake bake and set. A blend generally gives me a softer result than using a large amount of whey by itself.
Plant protein can work, but it tends to be more absorbent and may require recipe testing or additional liquid.
Does Protein Powder Still Contain Protein After Baking?
Yes. Baking protein powder does not remove the protein from the recipe.
Heat changes the protein's structure, which is called denaturation, but it does not make the protein disappear.
Why Did My Protein Loaf Turn Out Dry or Rubbery?
The most likely causes are too much protein powder, not enough liquid, or overbaking.
Different protein powders absorb liquid differently. Your loaf can also become dry if you continue baking it long after the center has set.
Start checking it around the 50-minute mark.
Why Is the Center of My Loaf Gummy?
The loaf may be underbaked, made with too much liquid, or sliced before it cooled.
Test the deepest part of the loaf with a toothpick. Then allow it to cool completely before cutting into it.
Why Did the Fruity Pebbles on Top Turn Brown?
The cereal pieces are thin and toast quickly under direct oven heat.
Bake the loaf on the center rack. If the top has enough color before the middle is done, loosely cover it with foil.
Can I Use Regular Cake Mix?
Yes.
Regular yellow, white, or vanilla cake mix should work, but it will change the calories, sugar, and nutrition per slice.
Can I Make This Without Eggs?
I have not tested this loaf without eggs.
The eggs help the cake rise and give the batter enough structure to support the added protein powder. An egg replacement may produce a denser loaf.
What Do Fruity Pebbles Taste Like in Cake?
Fruity Pebbles add a sweet citrus and berry-like cereal flavor.
The flavor is similar to the fruity milk left at the bottom of the cereal bowl. Inside the cake, the cereal softens and blends into the vanilla base rather than staying crunchy.
You Might Also Like
If you love high-protein cereal desserts as much as I do, these recipes are worth making next.
Final Thoughts
This Fruity Pebbles Protein Loaf Cake came out soft, colorful, and packed with the cereal flavor I wanted.
It is an easy way to turn boxed cake mix into a higher-protein breakfast or dessert without making the recipe complicated. Let the loaf cool, cut it into 10 slices, and keep it in the refrigerator when you need something sweet that still has 15 grams of protein.
Save the recipe and tag me at @bakedlean when you make it.
Fruity Pebbles Protein Loaf Cake (High Protein)
Ingredients
- 1 box zero-sugar yellow cake mix
- 4 scoops vanilla protein powder
- 1 box (1 oz) sugar-free vanilla pudding mix
- 3 large eggs
- 1 cup skim milk
- 1/2 cup nonfat Greek yogurt
- 1 cup Fruity Pebbles cereal for the batter
- 1/2 cup Fruity Pebbles cereal for the top
- 16 oz cold nonfat Greek yogurt
- 1 package (1 oz) zero-sugar white chocolate pudding mix
- 1 scoop vanilla protein powder preferably a whey and casein blend
- 1/3 cup Fruity Pebbles cereal plus more for topping if desired
Equipment
Method
- Preheat the oven to 350°F. Grease a 9×5-inch loaf pan or line it with parchment paper.
- Add the zero-sugar yellow cake mix, vanilla protein powder, and sugar-free vanilla pudding mix to a large mixing bowl. Whisk until evenly combined and break apart any visible clumps.
- Add the eggs, skim milk, and Greek yogurt. Mix until the batter is smooth and no dry pockets remain. The batter should be thick but spreadable. Add additional skim milk 1 tablespoon at a time only if needed.
- Gently fold 1 cup of Fruity Pebbles into the batter with a silicone spatula. Stop mixing once the cereal is evenly distributed.
- Transfer the batter to the prepared loaf pan and smooth the top into an even layer.
- Sprinkle the remaining ½ cup of Fruity Pebbles over the batter. Press the cereal lightly into the surface so it stays attached during baking.
- Bake for 50 to 60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Loosely cover the top with aluminum foil if the cereal begins browning before the center is fully baked.
- Let the loaf cool in the pan for 15 minutes. Lift it from the pan and transfer it to a wire rack. Allow the loaf to cool completely before adding the frosting.
- Add 16 ounces of cold nonfat Greek yogurt to a medium mixing bowl.
- Sprinkle the zero-sugar white chocolate pudding mix and vanilla protein powder over the yogurt.
- Whip with a hand whisk or electric hand mixer for 60 to 90 seconds, or until the mixture is smooth, light, and fluffy. The frosting should be thick enough to hold its shape on a spoon.
- Gently fold in ⅓ cup of Fruity Pebbles with a silicone spatula.
- Spread the fluffy yogurt frosting evenly over the completely cooled loaf.
- Top with additional Fruity Pebbles immediately before serving for the best color and crunch.
- Slice the loaf into 10 servings and serve chilled or at room temperature.
Nutrition
Notes
Fruity Pebbles Protein Loaf Cake Tips & Expert Strategy
TEXTURE NOTE: This loaf bakes up soft and tender with a moist crumb, topped with a thick whipped mousse-like frosting. SUBSTITUTION WARNING: A whey and casein blend works best. Using 100% whey protein powder will cause the cake to dry out and make the frosting chalky. BETTER LATER NOTE: The loaf must be completely cool before frosting. Store covered in the fridge, where the flavors meld together nicely overnight. SERVING TIP: Top with additional fresh Fruity Pebbles right before serving to maintain the best crunch against the creamy frosting.Tried this recipe?
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One response to “Fruity Pebbles Protein Loaf Cake (High-Protein Recipe)”
Good recipe
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