These birthday cake brownies are a funfetti cake baked in a 9X9-inch pan topped with brownie batter that is swirled in. You get both sprinkle cake and brownie batter all in one! There is no need to compromise between birthday brownies and a colorful birthday cake for your birthday party.
These birthday cake brownies are a delicious bottom layer of funfetti cake with homemade brownies on top swirled together. Each layer is a great recipe developed to make a delicious cake and the best brownies on their own. Together, they make a delicious treat you will want for every birthday!
For more brownie recipes try, Red Velvet Brownies, Turtle Brownies, and Oreo Brownies.
Why This Recipe Works
- Delicious combination- The birthday cake and brownies complement each other so well! The light fluffy vanilla cake flavors mixed with the rich chocolate brownie flavor works so well.
- Light and fun- Combining the decadent brownie with a light fluffy and colorful cake combines the rich chocolate color with bright rainbow fun!
- Easy recipe- This recipe is very simple to make and is broken down into very simple steps. You simply make 2 batters and bake them together! Bother were designed to be simple enough to be your first recipes.
- Homemade goodness- This cake is so moist and delicious you will never want to use a boxed cake mix again. The brownies were also designed to outperform any brownie mix. Together, they show how much better homemade is!
Here are some notes on the ingredients. For a full list of ingredients, check out the recipe card below.
- Unsalted butter- For the cake, pull it out 2 hours before baking so it is softened. For the frosting, pull it out 30 minutes before using so it is slightly cold.
- Oil- Use canola oil or vegetable oil.
- Clear vanilla extract- This is an imitation vanilla.
- Sour cream- Use full fat sour cream. Pull this out 2 hours before baking.
- Eggs- Pull the large out 2 hours before baking to get to room temperature.
- Buttermilk- Use full fat or reduced fat buttermilk. Pull this out 2 hours before baking.
- Rainbow sprinkles- Use Jimmie sprinkles. Rainbow Jimmies won't bleed too much into the cake. Non-peril sprinkles bleed into the cake and shouldn't be used.
- Powdered sugar- Make sure to sift it to avoid a gritty frosting.
- Unsweetened cocoa powder- I strongly recommend dutch process cocoa powder for a more rich chocolate flavor. This is the one I used.
- Chocolate Chips- Use semi-sweet chocolate for the best flavor as milk chocolate will be too sweet.
Step By Step Instructions- Cake Layer
Here is how to make and bake this birthday cake brownies cake layer.
STEP 1: Prep. Preheat the oven to 350°F. Then, spray a 9X9 inch square pan with baking nonstick spray. Line the bottom of the pan with parchment paper and spray it again.
STEP 2: Dry ingredients. In a medium bowl, sift together the all purpose flour, baking powder, and salt.
STEP 3: Beat butter. In a separate bowl, use a mixer to beat the butter for 3 minutes until it is light and fluffy.
STEP 4: Wet ingredients. Add the sour cream, vanilla extract, and eggs to the butter. Mix it on medium speed until combined. Use a rubber spatula to scrape the sides of the bowl to make sure it is all incorporated.
STEP 5: Combine. Add ⅓rd of the dry ingredients and half of the buttermilk and mix it in on low speed. Once combined add another ⅓rd of the flour mixture and the remaining buttermilk. Finish with the remaining dry ingredients.
STEP 6: Add sprinkles. Use a rubber spatula to fold the sprinkles into the batter.
STEP 7: Pour batter. Add the cake batter to the prepared pan and spread it into an even layer.
Step By Step Instructions- Brownie Layer
Here is how to make and bake this birthday cake brownie layer.
STEP 1: Dry ingredients. In a small bowl, sift together the flour, cocoa powder, cornstarch, and salt.
STEP 2: Beat egg. Using a stand mixer with whisk attachment, beat the sugar and egg on high speed for 5 minutes.
STEP 3: Wet ingredients. Add the melted butter, oil, and vanilla extract and mix on low until it is combined.
STEP 4: Combine. Add the dry ingredients in and mix on low speed until nearly combined.
Use a rubber spatula to fold in the chocolate chips, making sure to scrape the sides of the bowl as well.
STEP 5: Scoop batter. Use a tablespoon to dollop the brownie batter on top of the birthday cake layer spread evenly. Use a butter knife to swirl the batter.
STEP 6: Bake. Bake it for 30-35 minutes. It is done when an inserted toothpick into the middle of the cake comes out with only moist crumbs from the brownie and clean of cake crumbs.
If the brownie looks to have raw batter add 3-4 minutes of baking time.
STEP 7: Cool. Let the cake cool in the pan for 10 minutes before transferring it to a cooling rack. Cool it completely before decorating.
STEP 8: Decorate. In a mixing bowl mix the powdered sugar, vanilla extract, and milk together. Then, lightly drizzle the glaze on top of the cake.
I recommend adding additional sprinkles on top as well for a brighter birthday cake look.
Expert Baking Tips
When you are baking the brownies, you need to be careful when adding in the rest of the ingredients after the eggs are beaten.
If they are added in too fast, the eggs' air will deflate and you won't get as much of a rise from the brownies.
Make sure to spray the pan with baking non-stick spray, so the cake doesn't stick to the pan. It is also a good idea to place parchment paper on the bottom of the tray as well.
This means that the brownies were too under done. You will probably have extremely fudgy brownies. Bake the brownies again for another 5-10 minutes to cook them more.
This means the brownies are over baked. Make sure when you bake these, the center is slightly under done. You should get moist brownie crumbs when testing with a toothpick.
Yes you can. It will just make thick birthday cake brownies.
Storing and Freezing
Store these birthday cake brownies in an airtight container like a cake carrier. Store in the fridge up to 5 days.
You can freeze the birthday cake brownies in individual brownie slices. Place in an airtight container and freeze up to 30 days.
Other Cake Recipes To Try
Make sure to leave a STAR REVIEW if you loved this recipe! Make sure to tag me on Instagram @stephaniesweettreats. To get more ideas follow me on Pinterest.
Birthday Cake Brownies
- 1 ¾ cup All-purpose flour
- ½ tablespoon Baking powder
- ½ teaspoon Salt
- ½ cup Unsalted butter room temperature
- ¾ cup White granulated sugar
- ¼ cup Sour cream room temperature or plain yogurt
- ½ tablespoon Clear imitation vanilla see notes
- 2 Large eggs room temperature
- ½ cup Buttermilk room temperature
- ⅓ cup Rainbow jimmie sprinkles
- ½ cup White granulated sugar
- 1 Large egg room temperature
- 2 tablespoon Unsalted butter melted
- 2 tablespoon Oil canola or vegetable
- 1 teaspoon Pure vanilla extract
- 3 tablespoon All-purpose flour
- ¼ cup Unsweetened cocoa powder
- ½ tablespoon Cornstarch
- ½ teaspoon Salt
- ¼ cup Semi-sweet chocolate chips
- ½ cup Powdered sugar
- 1 tablespoon Milk
- 1 teaspoon Pure vanilla extract
- Preheat the oven to 350°F. Spray a 9X9-inch pan with baking nonstick spray. Line the bottom of the pan with parchment paper. Spray again.
- In a medium bowl, mix the flour, baking powder, and salt. Set aside.1 ¾ cup All-purpose flour, ½ tablespoon Baking powder, ½ teaspoon Salt
- Using a mixer, beat the butter and sugar on high speed for 3 minutes. The butter should be light and fluffy.½ cup Unsalted butter, ¾ cup White granulated sugar
- Then, add in the sour cream, vanilla, and eggs. Mix on medium until combined. You will need to scrape the bowl with a rubber spatula to make sure it is all combined.¼ cup Sour cream, ½ tablespoon Clear imitation vanilla, 2 Large eggs
- Add ⅓rd of the dry ingredients and half of the buttermilk and mix on low speed. Add another ⅓rd of the dry ingredients and the rest of the buttermilk. Then, finish with the rest of the dry ingredients.½ cup Buttermilk
- Take off the mixer and fold in the sprinkles. Spread the cake batter evenly into the prepared pan.⅓ cup Rainbow jimmie sprinkles
- In a small bowl, mix the flour, cocoa powder, cornstarch, and salt. Set aside. Using a mixer with a whisk attachment, beat the sugar and egg on high speed for 5 minutes.½ cup White granulated sugar, 1 Large egg, 3 tablespoon All-purpose flour, ¼ cup Unsweetened cocoa powder, ½ tablespoon Cornstarch, ½ teaspoon Salt
- Add in the melted butter, oil, and vanilla and mix on low until just combined. Add in the dry ingredients and mix until mostly combined.2 tablespoon Unsalted butter, 2 tablespoon Oil, 1 teaspoon Pure vanilla extract
- Take off the mixer and mix use a rubber spatula to scrape the bowl. Then, add in the chocolate chips.¼ cup Semi-sweet chocolate chips
- Use a Tablespoon to scoop the batter on top of the cake. Place it in spread out dollops. Use a butter knife to swirl in the batter.
- Bake for 30-35 minutes until a took pick inserted comes out clean with cake crumb, but moist crumbs for brownie batter. If the brownie part looks like raw batter, bake for another 3-4 minutes.
- Let the cake sit in the hot pan for 10 minutes. Then, transfer to a cooling rack. Cool completely before decorating
- In a small bowl, mix the powdered sugar, vanilla, and milk. Lightly drizzle the glaze on top of the cake. I also topped it with more sprinkles.½ cup Powdered sugar, 1 tablespoon Milk, 1 teaspoon Pure vanilla extract
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