High-Protein Lemon Blueberry Upside-Down Cake

This High-Protein Lemon Blueberry Upside-Down Cake is the blueberry version of the pineapple upside-down cake I recently made, and I might like the blueberry topping even more. Fresh blueberries, brown sugar, lemon juice, and lemon zest go into the bottom of the pan before the batter is added.

After baking, the whole cake gets flipped onto a serving plate to reveal a soft, jammy blueberry-lemon topping. FitFlour and Pillsbury Zero Sugar cake mix help each of the eight slices reach approximately 165 calories and 11 grams of protein without turning the cake dry or chalky.

Bake it lower and slower at 325°F for 40–45 minutes, until a toothpick inserted into the cake portion comes out clean, then give it a 15–20 minute rest before inverting. Do not overbake it, or the cake can become dry. The fruit becomes the topping, so there is no frosting to make.

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• Healthy Cherry Pineapple Dump Cake
• High-Protein Iced Animal Cracker Loaf Cake

Why You'll Love This Lemon Blueberry Cake

• 11 grams of protein per slice: FitFlour adds most of the extra protein while the cake mix keeps the texture closer to a traditional cake.
• About 165 calories: That estimate is for one-eighth of the cake, including the blueberry and brown sugar topping.
• No frosting needed: The baked blueberries become the topping when you flip the cake.
• Fresh lemon and blueberry flavor: Lemon zest supplies the aroma while lemon juice seasons the fruit layer.
• Easy cake-mix base: You get a short ingredient list without measuring a long set of dry ingredients.

The Cake Mix and FitFlour Strategy

I use 1 cup of Pillsbury Zero Sugar cake mix with ¾ cup FitFlour instead of replacing all of the dry mix. FitFlour provides 18 grams of protein per ¼ cup, so ¾ cup contributes about 54 grams of protein to the whole cake.

Keeping cake mix in the formula matters because I still want this to eat like cake. The eggs and skim milk add more protein, while unsweetened applesauce gives the batter moisture without adding oil.

What Makes This an Upside-Down Cake?

The topping goes into the pan first: brown sugar, blueberries, lemon zest, and lemon juice. The batter is spread over that fruit layer, and the blueberries soften into the sugar and lemon as everything bakes.

After a 15–20 minute rest, place a serving plate over the pan and flip the whole cake. The bottom becomes the top, leaving the blueberry-lemon layer in place of frosting.

Ingredients

Lemon Blueberry Topping

• Cooking spray, for the pan
• 3 tablespoons brown sugar
• 1¼ cups fresh blueberries, or a little more if desired
• Zest of 1 lemon
• 2 tablespoons fresh lemon juice

High-Protein Cake Batter

• 1 cup Pillsbury Zero Sugar cake mix, dry
• ¾ cup FitFlour
• ½ teaspoon baking powder
• 3 large eggs
• ½ cup unsweetened applesauce
• ½ cup water
• ½ cup skim milk
• Splash of vanilla extract

Ingredient Notes

FitFlour

FitFlour supplies much of the protein in this cake. Whisk it thoroughly with the cake mix and baking powder before adding the wet ingredients so the dry ingredients are evenly dispersed.

Pillsbury Zero Sugar Cake Mix

Use 1 cup of the dry mix. Do not prepare the box mix first; the cake mix is one dry ingredient in the batter developed here.

Fresh Blueberries

I tested the cake with 1¼ cups fresh blueberries. A few extra berries are fine for a heavier fruit layer, but fresh berries are the recommendation for recreating the tested cake.

Lemon Zest and Juice

Zest the lemon before juicing it. The juice adds acidity to the fruit layer, while the zest gives the cake its strongest fresh-lemon aroma.

Unsweetened Applesauce

Unsweetened applesauce keeps the batter moist without adding oil or another unknown amount of sugar.

Skim Milk

Skim milk adds moisture and a little more protein without much fat. Other milks can change the macros and may alter the batter slightly.

Why I Bake This Cake at 325°F

The fruit layer is wet, and the batter contains a substantial amount of FitFlour. Baking at 325°F gives the center time to set without the outside getting too far ahead.

The lower temperature also limits excessive doming, which helps the inverted cake sit more evenly on the serving plate. Start checking at 40 minutes and bake for 40–45 minutes at 325°F, until a toothpick inserted into the cake portion comes out clean. Do not overbake, because the cake can become dry.

Equipment

• 8-inch round cake pan
• Digital kitchen scale
• Silicone spatula
• Two mixing bowls
• Whisk
• Serving plate larger than the cake pan
• Oven mitts
• Thin knife

The 8-inch pan matters because changing the diameter changes the batter depth and baking time. A scale is useful for keeping higher-protein baking ingredients consistent, and a silicone spatula spreads the batter without disturbing the blueberries.

Tools I Use for This Recipe

FitFlour (10% Off)

This is the tested high-protein flour used in the cake batter and the main reason each slice reaches 11 grams of protein.

Duncan Hines Keto Friendly Yellow Cake Mix

This is a suggested zero-sugar cake-mix alternative. I tested the recipe with Pillsbury Zero Sugar cake mix, so texture and nutrition may vary by brand.

USA Pan 8-Inch Round Cake Pan

The tested recipe uses an 8-inch round pan. This is a suggested option that keeps the intended batter depth and baking range.

This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases.

How to Make High-Protein Lemon Blueberry Upside-Down Cake

1. Prepare the Oven and Pan

Preheat the oven to 325°F. Coat the bottom and sides of an 8-inch round cake pan well with cooking spray.

2. Mix the Dry Ingredients

Whisk the Pillsbury Zero Sugar cake mix, FitFlour, and baking powder together until they are evenly combined.

3. Mix the Wet Ingredients

In a separate bowl, whisk the eggs, unsweetened applesauce, water, skim milk, and vanilla until evenly combined.

4. Start the Blueberry Topping

Sprinkle the brown sugar evenly across the bottom of the prepared pan. Spread the blueberries over the sugar instead of piling them in the center.

5. Add the Lemon

Sprinkle the lemon zest over the blueberries, then drizzle the lemon juice over the fruit.

6. Make the Batter

Pour the wet mixture into the dry ingredients. Stir just until evenly combined, scraping the bottom and sides of the bowl so no dry pockets remain.

7. Add the Batter to the Pan

Carefully spoon or pour the batter over the blueberries. Spread it into an even layer without pushing the spatula down into the fruit.

8. Bake for 40–45 Minutes

Bake at 325°F for 40–45 minutes, until the center looks set and a toothpick inserted into the cake portion comes out clean. Test away from a blueberry so fruit moisture is not mistaken for raw batter, and do not overbake or the cake can become dry.

9. Rest for 15–20 Minutes

Remove the cake from the oven and leave it in the pan for 15–20 minutes so it can settle before inversion.

10. Flip the Cake

Run a thin knife around the edge if needed. Place a serving plate face-down over the pan, hold the plate and pan firmly together with oven mitts, and flip in one controlled motion. Slowly lift away the pan and spoon any stuck blueberries back onto the cake.

11. Cool and Slice

Let the cake cool further before cutting it into eight slices.

Expert Tips

• Whisk the dry ingredients well: Even distribution prevents pockets of FitFlour or baking powder.
• Zest before juicing: A whole lemon is much easier to zest than two squeezed halves.
• Spray the entire pan: The fruit and sugar need to release along with the cake.
• Keep the blueberries under the batter: Spread gently so the fruit stays concentrated at the bottom.
• Wait before flipping: Give the cake 15–20 minutes to settle, but do not let the fruit layer cool completely in the pan.
• Use a large serving plate: Choose one wider than the cake so blueberry juices stay contained.

Frequently Asked Questions

Can I use frozen blueberries?

Fresh blueberries are the tested recommendation. Frozen berries can release more water and may change the topping and baking time.

Can I use regular cake mix?

That is a variation. This cake and its nutrition estimate were developed with Pillsbury Zero Sugar cake mix, so another mix will change the sweetness and macros.

Can I replace FitFlour with regular flour?

Not for this specific high-protein recipe. FitFlour supplies a large portion of the protein, and replacing it with all-purpose flour would materially change both the nutrition and batter.

Can I use Greek yogurt instead of applesauce?

The tested cake uses unsweetened applesauce. Greek yogurt would be a suggested substitution, and results may vary by brand; moisture, texture, and baking time may need adjustment.

Can I use another milk?

The tested recipe and nutrition estimate use skim milk. Another dairy or plant milk is a suggested substitution; brands vary, so the macros and batter may change slightly.

Why did my cake stick to the pan?

Spray the entire inside of the pan and follow the 15–20 minute rest before inverting. If a few blueberries stay behind, spoon them back onto the top.

Why is there blueberry juice on top?

That is expected. The blueberries release juice as they bake, and it mixes with the lemon and brown sugar to create the soft, jammy topping.

How do I know when the cake is done?

Start checking at 40 minutes. The cake is done when the center looks set and a toothpick inserted into the cake portion comes out clean, usually within 40–45 minutes. Avoid testing directly through a blueberry, and do not overbake or the cake can become dry.

Variations and Serving Ideas

• Add a few extra blueberries for a fruitier topping.
• Add extra lemon zest over the finished cake for more lemon aroma without changing the liquid in the fruit layer.
• Serve with vanilla Greek yogurt for an additional protein option.
• Add whipped cream when the extra calories fit your preference.

Storage

Let the cake cool completely, then store leftover slices in an airtight container in the refrigerator for 3–4 days. Eat it cold, let it approach room temperature, or warm a slice briefly in the microwave.

I have not tested freezing this cake, so the texture of the blueberry topping after thawing is uncertain.

You Might Also Like

• Double Espresso Chocolate Protein Loaf Cake
• High-Protein Lemon Cream Pie Baked Oats
• High-Protein Blueberry Donut Holes

Final Thoughts

I like that the protein boost comes from FitFlour instead of turning the entire recipe into protein powder. You still get cake mix, real brown sugar, and a generous fresh blueberry topping with lemon.

Bake it at 325°F for 40–45 minutes, until a toothpick comes out clean, without overbaking; then wait 15–20 minutes before flipping, and put any blueberries that stay in the pan right back on top. At approximately 165 calories and 11 grams of protein per slice, this is one I'll make again.

If you make it, leave a rating and comment below and tell me how the flip went.

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Jacob Hensley

High-Protein Lemon Blueberry Upside-Down Cake

5 from 1 vote

A soft lemon blueberry upside-down cake made with Pillsbury Zero Sugar cake mix and FitFlour, then flipped to reveal a jammy blueberry, brown sugar, and fresh lemon topping.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 45 minutes mins

Rest Before Inverting 20 minutes mins

Total Time 1 hour hr 20 minutes mins

Ingredients

  

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Lemon Blueberry Topping

• cooking spray for the pan
• 3 tablespoons brown sugar
• 1 1/4 cups fresh blueberries or a little more if desired
• 1 lemon lemon zest
• 2 tablespoons fresh lemon juice

Cake Batter

• 1 cup Pillsbury Zero Sugar cake mix dry
• 3/4 cup FitFlour
• 1/2 teaspoon baking powder
• 3 large eggs
• 1/2 cup unsweetened applesauce
• 1/2 cup water
• 1/2 cup skim milk
• 1 splash vanilla extract

Equipment

• 8-inch round cake pan
• Mixing Bowls two
• Whisk
• Silicone Spatula
• Digital Kitchen Scale
• Serving plate larger than the cake pan
• Oven mitts

Method

 

1. Preheat the oven to 325°F. Spray the bottom and sides of an 8-inch round cake pan well with cooking spray.
2. Whisk the Pillsbury Zero Sugar cake mix, FitFlour, and baking powder together until evenly combined.
3. In a separate bowl, whisk together the eggs, applesauce, water, skim milk, and vanilla.
4. Sprinkle the brown sugar evenly across the bottom of the prepared pan.
5. Spread the blueberries evenly over the brown sugar.
6. Sprinkle the lemon zest over the blueberries and drizzle with the lemon juice.
7. Add the wet ingredients to the dry ingredients and stir just until evenly combined, scraping the bottom and sides of the bowl.
8. Carefully pour or spoon the batter over the blueberries and spread it into an even layer without disturbing the fruit.
9. Bake at 325°F for 40–45 minutes, until the center is set and a toothpick inserted into the cake portion comes out clean. Test away from a blueberry, and do not overbake or the cake can become dry.
10. Let the cake rest in the pan for 15–20 minutes.
11. Run a thin knife around the edge if needed. Place a serving plate face-down over the pan, hold the plate and pan together with oven mitts, and flip in one controlled motion. Slowly lift away the pan and spoon any stuck blueberries back onto the cake.
12. Let the cake cool further before cutting it into eight slices.

Nutrition

Calories: 165kcalCarbohydrates: 23gProtein: 11gFat: 2g

Notes

Blueberries: Fresh blueberries are the tested recommendation. Frozen berries may add water and change the topping or baking time.

Pan and bake: Use an 8-inch round cake pan and bake at 325°F for 40–45 minutes, until a toothpick inserted into the cake portion comes out clean. Do not overbake or the cake can become dry. Rest 15–20 minutes before inverting.

Storage: Cool completely and refrigerate in an airtight container for 3–4 days.

Nutrition: Estimated per one-eighth of the cake and including the complete blueberry, lemon, and brown sugar topping. Nutrition can vary based on the ingredients and brands used.

Tried this recipe?

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