These Chocolate Banana S'mores Brownies are a soft, brownie-style dessert that brings ripe banana, rich cocoa, and s'mores toppings together in one pan. The batter starts with three very ripe bananas, cocoa powder, and an entire vanilla protein shake, then gets topped with chocolate chips, marshmallows, and chunks of graham cracker.
I use a cup-for-cup zero-calorie sugar alternative plus sugar-free chocolate chips and marshmallows when I can find them. That lowers the added sugar, but this is not a keto dessert—it still contains bananas, all-purpose flour, and graham crackers.
Everything for the chocolate banana batter goes into a blender, gets poured into an 8×8-inch pan, and is topped before baking. My tested batch was done at exactly 32 minutes at 350°F.
Try These Next
If you have more overripe bananas, try my High-Protein Banana Bread Skillet, High-Protein Banana Bread Muffins, or Cinnamon Swirl Banana Protein Cake.
Why You'll Love This Recipe
- One blender: The bananas and the rest of the batter ingredients blend together until smooth.
- Three very ripe bananas: This is exactly the kind of recipe to save for bananas you forgot on the counter.
- Chocolate, banana, and s'mores: Cocoa flavors the batter while chocolate chips, marshmallows, and graham crackers cover the top.
- Lower-sugar swaps: A zero-calorie sugar alternative and sugar-free toppings help reduce added sugar.
- Protein shake in the batter: An entire 11-ounce vanilla protein shake supplies the liquid.
- Tested bake time: My batch was done at exactly 32 minutes in an 8×8-inch pan.
Use Really Ripe Bananas
Use three very ripe bananas with lots of dark spots and soft fruit. They blend smoothly and provide the obvious banana flavor that needs to stand up underneath the chocolate and s'mores topping.
If your bananas are barely yellow, wait. This recipe depends on the moisture and flavor of heavily ripened bananas.
Ingredients
Chocolate Banana Batter
- 3 very ripe bananas
- 1 large egg
- 1 cup all-purpose flour
- ½ cup unsweetened cocoa powder
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- 1 cup cup-for-cup zero-calorie sugar alternative
- ½ teaspoon salt
- 1 teaspoon vanilla extract
- 1 (11-ounce) vanilla protein shake
I tested the recipe with Equate Vanilla Protein Shake. A similar ready-to-drink vanilla shake may work, but sweetness, thickness, texture, and nutrition can vary by brand.
S'mores Topping
- ½ cup sugar-free chocolate chips
- ⅓ cup sugar-free mini marshmallows, or regular mini marshmallows
- 2 full graham cracker sheets, roughly crushed
Ingredient Notes
Vanilla Protein Shake
I used an 11-ounce Equate Vanilla Protein Shake. It supplies all of the batter's liquid while adding extra protein. Other ready-to-drink vanilla shakes are suggested substitutions; results may vary by brand, and small adjustments to moisture, timing, or texture may be needed.
Cocoa Powder
Use unsweetened cocoa powder so the banana batter itself has a deep chocolate flavor.
Sugar-Free Chocolate Chips and Marshmallows
I use sugar-free versions when available. Regular chocolate chips and regular mini marshmallows also work, but they will change the sugar, calories, and other nutrition values.
Graham Crackers
Roughly crush two full graham cracker sheets. Keep visible pieces rather than turning them into crumbs so the topping has real graham-cracker texture.
Equipment
- Blender
- 8×8-inch baking pan
- Silicone spatula
- Measuring cups and spoons
- Toothpick
- Wire cooling rack
The 8×8-inch pan is important because a different pan changes the depth of the batter and the baking time.
Tools I Use for This Recipe
ChocZero Sugar-Free Mini Marshmallows
A suggested sugar-free mini marshmallow that gives the topping its toasted s'mores texture.
Hershey Zero-Sugar Chocolate Chips
A suggested lower-sugar chocolate chip option for covering the brownies with melted chocolate.
USA Pan 8-Inch Square Pan
A suggested 8×8-inch metal pan that matches the tested pan size and keeps the batter at the intended depth.
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How to Make Chocolate Banana S'mores Brownies
1. Prepare the Pan
Preheat the oven to 350°F. Spray an 8×8-inch baking pan with cooking spray.
2. Blend the Batter
Add the bananas, egg, flour, cocoa powder, baking powder, baking soda, sugar alternative, salt, vanilla, and protein shake to a blender. Blend until completely smooth, stopping to scrape down any flour or cocoa around the sides.
3. Fill the Pan
Pour the batter into the prepared pan and spread it evenly into the corners.
4. Add the S'mores Topping
Sprinkle the chocolate chips over the batter. Add the marshmallows, then finish with the roughly crushed graham crackers. Distribute everything so each square gets all three toppings.
5. Bake for 30–32 Minutes
Bake at 350°F for 30–32 minutes. My batch was done at exactly 32 minutes. Insert a toothpick into the center of a brownie rather than through a melted chocolate chip or marshmallow.
Do not keep baking just because the center feels soft while hot. Three bananas and a full protein shake keep these brownies moist. If the toothpick comes out without wet batter, remove the pan from the oven.
6. Cool Before Slicing
Cool in the pan for at least 20–30 minutes. The center continues setting as it cools, and the squares cut much more cleanly after that rest.
What Is the Texture Like?
The texture is like soft, moist chocolate brownies with a clear banana flavor. They are not dense or fudgy like traditional boxed brownies; the ripe bananas and protein shake keep the center tender while the 8×8-inch pan gives them a brownie-style shape and thickness.
The bananas keep the center moist, while the chocolate chips, marshmallows, and graham crackers give the top three different textures.
Expert Tips
- Wait for very ripe bananas. The bananas should be soft and heavily spotted.
- Blend until smooth. Do not leave pockets of dry cocoa or flour.
- Keep the graham crackers chunky. Pieces give the topping more texture than fine crumbs.
- Check the center of a brownie with the toothpick. Melted chocolate is not raw batter.
- Do not overbake. My batch passed the toothpick test at 32 minutes.
- Let it cool. The center firms significantly as it comes down in temperature.
Variations
Regular S'mores Topping
Regular chocolate chips and mini marshmallows will work when sugar-free versions are unavailable. The nutrition will change.
Add Nuts
Suggested variation: Walnuts or pecans make sense with chocolate banana brownies, although I have not tested them in this version. If you try them, use a small amount on top so the batter is not overcrowded; texture and timing may vary.
Extra Graham Crackers
For more crunch, add a few extra graham cracker pieces after baking.
Frequently Asked Questions
Are these keto brownies?
No. Even with several sugar-free ingredients, bananas, all-purpose flour, and graham crackers contain carbohydrates.
Can I use regular sugar?
Suggested substitution: A cup-for-cup granulated sugar can replace the cup-for-cup sugar alternative, but I have not tested that version. Results and nutrition will vary, and small changes to moisture, timing, or texture may occur.
Can I use another protein shake?
A similar vanilla ready-to-drink protein shake should work. The tested recipe uses Equate Vanilla; results can vary by brand.
Can I use chocolate protein shake?
I have not tested it. It would make the brownies more intensely chocolate, while the tested version uses vanilla.
How do I know when it's done?
Start checking at 30 minutes. The center should look set, and a toothpick inserted into a brownie should come out without wet batter. Mine was done at 32 minutes.
Why are my brownies still soft?
Three bananas add substantial moisture, and the brownies firm as they cool. If the toothpick has wet batter, bake longer. If it comes out clean, let the pan cool before deciding the brownies are underdone.
Storage
Cool the brownies completely before storing them. Keep leftovers covered or in an airtight container, and refrigerate for longer storage.
Marshmallows and graham crackers naturally soften during storage, so the topping is best the day it is baked. Warm an individual square briefly in the microwave if you want the topping gooey again.
For freezing, wrap individual cooled squares and place them in a freezer-safe container. Thaw in the refrigerator or at room temperature. The graham cracker topping may be softer after freezing.
You Might Also Like
If chocolate is the main reason you're here, try my Quick & Easy Chocolate Protein Muffins. For more ripe-banana ideas, make my High-Protein Banana Oatmeal M&M Breakfast Cookies or Cinnamon Swirl Banana Protein Cake.
Nutrition Estimate
Estimated nutrition is approximately 285 calories, 12g protein, 53g carbohydrates, and 8g fat per serving, based on six equal squares, three medium bananas, an 11-ounce Equate Vanilla Protein Shake, a cup-for-cup zero-calorie sweetener, Hershey Zero-Sugar Chocolate Chips, ChocZero sugar-free mini marshmallows, and two standard graham cracker sheets. Nutrition varies by brand, banana size, topping choice, and portion size.
BAKE THIS NEXT
Chocolate Banana S'mores Brownies
Ingredients
- 3 bananas very ripe
- 1 large egg
- 1 cup all-purpose flour
- 1/2 cup unsweetened cocoa powder
- 1 cup cup-for-cup zero-calorie sugar alternative
- 1/2 teaspoon salt
- 1 teaspoon vanilla extract
- 1 11-ounce bottle vanilla protein shake Equate Vanilla tested
- 1/2 cup sugar-free chocolate chips
- 1/3 cup sugar-free mini marshmallows or regular mini marshmallows
- 2 full sheets graham crackers roughly crushed
- 1 teaspoon baking powder
- 1/2 teaspoon baking soda
Method
- Preheat the oven to 350°F. Spray an 8×8-inch baking pan with cooking spray.
- Add the bananas, egg, flour, cocoa powder, baking powder, baking soda, sugar alternative, salt, vanilla extract, and protein shake to a blender. Blend until completely smooth, scraping down the sides as needed.
- Pour the batter into the prepared pan and spread it evenly into the corners.
- Sprinkle the chocolate chips over the batter. Add the marshmallows, then finish with the roughly crushed graham crackers.
- Bake for 30–32 minutes. The tested batch was done at exactly 32 minutes. Insert a toothpick into the bread rather than through a chocolate chip or marshmallow; it is ready when no wet batter remains.
- Cool in the pan for at least 20–30 minutes before slicing into 6 squares.
Nutrition
Notes
- The tested recipe uses an 11-ounce Equate Vanilla Protein Shake and an 8×8-inch pan.
- The tested bake time was exactly 32 minutes at 350°F.
- Keep the graham crackers in visible pieces rather than fine crumbs.
- Cool for at least 20–30 minutes before slicing so the center can finish setting.
- Estimated nutrition is based on six squares and representative sugar-free topping brands. Nutrition varies by brand, banana size, topping choice, and portion size.
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