The Best Birthday Cake

Instructions

• Make the cake: Preheat the oven to 350°F (180°C). Lightly spray three 8-inch cake pans with nonstick spray. Line the bottoms with parchment paper rounds and spray again.
• In a large bowl, whisk together the sour cream, eggs, and egg whites until evenly combined. Add the vanilla and milk and whisk until incorporated.
• In the bowl of a stand mixer fitted with a paddle attachment, combine the granulated sugar and salt. Sift in the cake flour, baking soda, and baking powder. Mix on low speed to incorporate.
• Cut the butter into tablespoon-sized pieces. With the mixer running on low speed, add the butter to the dry ingredients, one piece at a time. Continue mixing until a sandy, coarse meal forms, 3–4 minutes.
• With the mixer running on low speed, pour in one-quarter of the wet ingredients at a time and mix to incorporate, scraping down the sides of the bowl between each addition. Continue mixing until the batter is smooth.
• Remove the bowl from the stand mixer and gently fold in the sprinkles with a rubber spatula.
• Divide the batter evenly between the prepared cake pans, tapping the pans on the counter a couple of times to release any large air bubbles.
• Bake the cakes for 25–30 minutes, until a toothpick inserted into the center of a cake comes out clean. 8. Set the pans on a wire rack and let the cakes cool completely, about 1 hour. Once cooled, run an offset spatula around the edges of the pans to loosen the cakes, then invert onto the rack and remove the parchment rounds.
• Meanwhile, make the frosting: In a large bowl with an electric hand mixer (or in a stand mixer fitted with the whisk attachment), whip the butter on medium speed until creamy, about 3 minutes.
• With the mixer running on low speed, add the powdered sugar, about 1 cup at a time. Once incorporated, add the cream, vanilla, and salt. Increase the mixer speed to high and beat for 3 minutes, until the frosting is fluffy.
• Assemble the cake: Using a large serrated knife, slice a thin layer off the top of each cake to create a flat surface. Discard the scraps.
• Smear a bit of frosting onto an 8-inch cake round set on top of a cake stand, then place a cake layer on the round. Use a large offset spatula to spread an even layer of frosting over the cake. Place another cake layer on top and frost. Place the last cake layer, bottom-side up, on top and spread a thin layer of frosting over the top and sides of the cake to make the crumb coat. Refrigerate for 15 minutes, until the frosting is set.
• Generously spread a thick, even layer of frosting over the top and sides of the cake. Decorate the cake with the remaining frosting and sprinkles as desired.
• Slice and serve. Cake can be kept at room temperature for 2 hrs and refrigerated for 3 days.
• Enjoy!