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Cut slice of single layer funfetti cake partially removed from rest of the cake | All images © Beyond the Butter®

Single Layer Funfetti Cake

Author: Jennifer
Add a little fun to your next dessert with this 6 inch Single Layer Funfetti Cake! It is moist, tender, and mixed with a handful of rainbow jimmies! For added vanilla flavor, pair it with this small batch vanilla flour buttercream and top it with a mix of some of your favorite sprinkles! It's another easy and delicious single layer cake recipe you'll be sure to love!
5 from 2 votes
Prep Time 15 minutes
Cook Time 40 minutes
Total Time 55 minutes
Course Dessert
Cuisine American
Servings 4 servings


single layer funfetti cake

  • 1 cup Cake Flour
  • 1 teaspoon Baking Powder
  • ¼ teaspoon Salt
  • 5 tablespoon Unsalted Butter, room temperature
  • ½ cup Granulated Sugar
  • 1 Large Egg, room temperature
  • 1 teaspoon Vanilla Extract
  • cup Buttermilk
  • ¼ cup Rainbow Jimmies, or rainbow sprinkles

small batch vanilla flour buttercream frosting

  • 3 tablespoon All-Purpose Flour
  • ½ cup Granulated Sugar
  • ½ cup Milk
  • ¼ teaspoon Salt
  • ½ cup Unsalted Butter, room temperature and cut into pieces
  • 1 teaspoon Vanilla Extract

sprinkle mix (for cake decoration)

  • ¼ cup Rainbow Jimmies
  • ¼ cup Rainbow Nonpareils
  • ¼ cup Rainbow Confetti


single layer funfetti cake

  • Adjust the oven rack to the 2nd level mark (just above center) and preheat your oven to 350ºF. Generously spray a 6 inch round cake pan (6 x 3 is preferred) with a flour based baking spray. Line the bottom with parchment paper and lightly respray the top.
  • In a medium-size mixing bowl, sift together the cake flour, baking powder, and salt. Set to the side.
  • Usin your hand mixer and a medium-size mixing bowl or your stand mixer fitted with the paddle attachment, beat together the unsalted butter and granulated sugar on medium high speed until light in color and fluffy in texture.
  • Add in the egg and vanilla extract.
  • Switch the mixer speed to low, gradually adding the whisked dry mixture alternatively with the buttermilk. Mix until just combined. Fold in your rainbow jimmies (sprinkles).
  • Transfer your cake batter to the prepared pan, then bake for 35-40 minutes at 350ºF or until an inserted toothpick comes out clean. Note: a few crumbs on the toothpick is okay, but it should not be cake batter.
  • Cool for about 10 minutes in the pan, then carefully invert it onto a wire cooling rack to finish cooling completely. The cake should be completely cooled before frosting as well.

small batch vanilla flour buttercream frosting

  • Combine the all-purpose flour, granulated sugar, and salt in a small saucepan. Whisk together, then add in the milk and whisk once more until well combined.
  • Over low-medium heat bring the mixture to a near boil, continually stirring with a spatula. It's a good idea to run your spatula along the bottom of the saucepan as well as you stir. Your mixture will begin to thicken to the consistency of paste and will have a wet, glossy look to it. Do not leave this mixture left unattended at any point during this process.
  • Once the mixture begins to bubble, turn off the heat and continue to stir and scrape for 1-2 minutes more. This will help release some of the heat as well as remove some of the glossiness.
  • Evenly spread out the mixture onto a plate (preferably one with a lip or an edge) and immediately cover with plastic wrap, pressing it directly onto the top of the mixture. This will prevent a skin from forming over the top as it cools. The flour mixture must cool to room temperature before moving on to the next step. See notes below to help speed up the process slightly.
  • Before starting, make sure the unsalted butter is at room temperature and cut into cubes. Beat the butter on medium-high speed using a stand mixer or a hand mixer for 2-3 minutes or until it's light in color and fluffy in texture.
  • Switching the mixer speed to low, add the room temp flour mixture to the butter one spoonful at a time (not all at once). Let each spoonful mix into the frosting before adding more.
  • Once it's all been added, scrape down the sides of the bowl, add in the vanilla extract, and mix once more on medium speed until fully combined. If your frosting does end up having air bubbles, you can use a spatula to press the frosting along the sides of the bowl to remove them.
  • You can make either the thickened flour mixture or the flour buttercream 3-5 days in advance. Keep it stored in the refrigerator, then bring to room temperature when ready to use. For the vanilla flour buttercream, you should mix it again for 2-3 minutes with your hand mixer or stand mixer to bring it back to it's fluffy life.

assembling the funfetti cake

  • If desired, slice your cooled funfetti cake into 2 layers. Place the first layer onto a half sheet of parchment paper, a serving plate, or cake circle.
  • Add a thin layer of the frosting with an offset spatula to the top, then top with the remaining layer. If you'd like before adding the second layer, you can add a few sprinkles to the frosting.
  • Once the cake is frosted, add on your sprinkles or sprinkle mix, then enjoy!

Recipe Notes

Recipe times do not include making the frosting.
Because this is a thicker cake, my recommendation is to use the 6" x 3". If using a 6" x 2", note that the cake will more than likely come right up to the top of the cake pan.
To speed up the process of cooling your flour mixture, you can let it cool down in the refrigerator, then bring it out to let it come to room temperature. Both the thicken mixture and the butter need to be at room temperature.
Flour buttercream recipe inspired by the tips provided by my friend Lindsay from @theflourgirl_
Keyword funfetti butter cookies, funfetti cake, single layer cakes, single layer funfetti cake, small batch frosting, small batch vanilla flour buttercream, vanilla flour buttercream
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