Funfetti Cake

Step 1
Prepare cake: Preheat the oven to 350 degrees F (175 degrees C). Coat 3 (8-inch) round cake pans with baking spray with flour. Line the bottom of each cake pan with a piece of parchment paper cut to fit the bottom.

Step 2
Beat white sugar and butter together in the bowl of a stand mixer fitted with a paddle attachment at medium speed until mixture is light and fluffy, about 4 minutes. Add eggs, one at a time, beating on low speed until combined.

Step 3
Whisk together flour, baking powder, and salt in a separate bowl. Add flour mixture to butter mixture in 3 additions, alternating with milk, beginning and ending with flour mixture. Beat on low speed until blended after each addition. Beat in vanilla extract and sprinkles on low speed, about 20 seconds.

Step 4
Divide batter evenly among prepared pans, about 2 cups per pan.

Step 5
Bake in the preheated oven until a wooden pick inserted in center comes out clean, 25 to 28 minutes. Let cool in pans for 10 minutes. Invert onto a wire rack and let cool completely, about 30 minutes.

Step 6
Prepare the frosting: Beat butter in the bowl of a stand mixer fitted with a paddle attachment at medium speed until creamy, about 2 minutes. Add powdered sugar, salt, and vanilla. Beat at low speed until combined, about 30 seconds. Beat in sour cream. Increase speed to high and beat until fluffy, scraping down sides as needed, 1 1/2 to 2 minutes. Stir in sprinkles.

Step 7
Place 1 cake layer on a plate; spread with about 3/4 cup frosting. Repeat cake and frosting layers one more time. Top with remaining cake layer. Spread remaining frosting over top and sides of cake. Garnish with more sprinkles, if desired. Store cake loosely covered in the refrigerator.