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Easy Confetti Cake with Sour Cream Frosting
Tender, colorful, and unapologetically cheerful, this three-layer confetti cake brings bakery-level joy right to your kitchen. The secret here is starting with a convenient boxed mix, then completely transforming it with a rich, homemade buttercream. By whipping sour cream and salted butter into the powdered sugar, you'll create a tangy, smooth frosting that perfectly balances the sweetness of the cake. It's a foolproof dessert that guarantees smiles at any birthday or weekend celebration.
Ingredients
- 1 (15¼-oz.) pkg. confetti cake mix (plus ingredients listed on box for preparing cake)
- 1½ cups butter, softened
- 4½ cups unsifted powdered sugar
- ½ cup sour cream
- 1 tsp. vanilla extract
- ¼ cup rainbow candy sprinkles, plus more for garnish
Instructions
- 1Heat the oven to 350°F. Make the cake batter following the instructions on the box. Pour the batter evenly into three 6-inch round cake pans greased with baking spray.
- 2Bake until a wooden pick inserted into the centers comes out clean, 20 to 23 minutes. Let the cakes rest in the pans for 10 minutes before turning them out onto wire racks to cool completely, about 45 minutes. Cooling completely prevents the frosting from melting later.
- 3Whip the softened butter in a large bowl using an electric mixer on medium speed until smooth, about 2 minutes.
- 4Turn the mixer to low speed and slowly incorporate the powdered sugar, sour cream, and vanilla extract. Whip until fluffy, about 3 minutes, pausing occasionally to scrape down the sides of the bowl.
- 5Scoop about 1 cup of the finished frosting into a separate bowl and gently fold in the candy sprinkles.
- 6Set a cake plate on a stand or lazy Susan. Position one cake layer on the plate and cover the top with 1 cup of the plain frosting, leveling it with an offset spatula.
- 7Repeat with the remaining two cake layers and 2 cups of plain frosting. Coat the sides of the cake with a thin layer of frosting (about a half cup) to create a crumb coat. This traps loose crumbs so they don't ruin your final layer.
- 8Chill the cake in the refrigerator until the frosting becomes firm, about 30 minutes.
- 9Coat the sides of the chilled cake with a thicker layer of the reserved sprinkle frosting, smoothing it as you work. Transfer any leftover frosting into a piping bag fitted with a medium round tip.
- 10Pipe dollops of frosting around the top border of the cake. Finish by scattering extra sprinkles over the center.
Notes
- Make ahead: You can bake the cake layers a day in advance. Wrap them tightly in plastic wrap and store them at room temperature until you're ready to frost.
- Storage: Keep the frosted cake in an airtight container in the refrigerator for up to 4 days. Let it sit at room temperature for 30 minutes before serving for the best texture.
- Tip: Make sure your butter is truly softened to room temperature before whipping to avoid a lumpy buttercream.