Ingredients
For the Cake
- 3 cups (375g) all-purpose flour
- 2½ teaspoons baking powder
- ½ teaspoon baking soda
- ½ teaspoon salt
- 1 cup (226g) unsalted butter, softened
- 1¾ cups (350g) granulated sugar
- 4 large eggs, room temperature
- 1 tablespoon vanilla extract
- 1 cup (240ml) whole milk, room temperature
- ½ cup (120g) sour cream
- ¾ cup (120g) rainbow jimmies sprinkles (avoid nonpareils)
For the Vanilla Buttercream
- 1½ cups (340g) unsalted butter, softened
- 5 cups (600g) powdered sugar, sifted
- 2 teaspoons vanilla extract
- 3–4 tablespoons heavy cream or whole milk
- ¼ teaspoon fine salt
For Decorating
- Extra rainbow sprinkles
- White chocolate curls (optional)
Equipment
- Two 8-inch round cake pans
- Large mixing bowls
- Electric mixer
- Rubber spatula
- Cooling rack
- Offset spatula
- Cake turntable (optional)
Instructions
Step 1: Prepare the Oven
Preheat the oven to 350°F (175°C).
Grease and line two 8-inch round cake pans with parchment paper.
Step 2: Mix the Dry Ingredients
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
Step 3: Cream the Butter and Sugar
In a large mixing bowl, beat the softened butter and granulated sugar until light and fluffy, about 3–4 minutes.
Add the eggs one at a time, beating well after each addition.
Mix in the vanilla extract.
Step 4: Prepare the Batter
Alternately add the dry ingredients and the milk to the butter mixture, beginning and ending with the dry ingredients.
Fold in the sour cream until fully incorporated.
Gently fold in the rainbow sprinkles using a rubber spatula, taking care not to overmix.
Step 5: Bake
Divide the batter evenly between the prepared cake pans.
Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.
Cool the cakes in the pans for 10 minutes before transferring them to a wire rack to cool completely.
Step 6: Make the Buttercream
Beat the softened butter until creamy.
Gradually add the powdered sugar, mixing on low speed.
Add the vanilla extract, salt, and heavy cream, then beat on medium-high speed for 3–4 minutes until smooth and fluffy.
Step 7: Assemble the Cake
Place one cake layer on a serving plate or cake stand.
Spread an even layer of buttercream over the top.
Place the second cake layer on top and frost the top and sides of the cake.
Smooth the frosting with an offset spatula or create decorative swirls.
Step 8: Decorate
Press rainbow sprinkles around the sides or over the top of the cake.
Add white chocolate curls or additional frosting swirls if desired.
Slice and serve at room temperature.
Tips for Success
- Use rainbow jimmies sprinkles, as they hold their color better than nonpareils.
- Make sure all refrigerated ingredients are at room temperature before mixing.
- Do not overmix the batter after adding the flour or sprinkles.
- Cool the cake layers completely before frosting.
- Chill the cake for 20 minutes after applying a crumb coat for a smoother finish.
Serving Suggestions
Serve Confetti Layer Cake with:
- Vanilla ice cream
- Fresh strawberries or raspberries
- Whipped cream
- Hot coffee
- Cold milk
- Sparkling lemonade
- Birthday party treats
Storage
Store the cake covered at room temperature for up to 2 days or refrigerate for up to 5 days. Bring to room temperature before serving for the best flavor and texture. The unfrosted cake layers can be wrapped tightly and frozen for up to 3 months. The buttercream can also be made ahead and refrigerated for up to 1 week before re-whipping.
Nutrition (Per Slice, Approximate)
- Calories: 560
- Carbohydrates: 68g
- Protein: 5g
- Fat: 30g
- Saturated Fat: 18g
- Fiber: 1g
- Sugar: 49g
- Sodium: 220mg
