3 cups cake flour
1 ½ cups sugar
1.5 tsp salt
16 Tbl unsalted butter, cut into 16 pieces and softened
1 recipe Large-Batch Vanilla Frosting
Directions for the Cake:
Adjust oven rack to middle position and heat oven to 350 degrees. Grease three 8-inch round cake pans, line with parchment paper, grease parchment, and flour pans. Pulse 1/2 cup sprinkles in food processor until coarsely ground, 8 to 10 pulses; set aside. Whisk together egg whites, milk, and vanilla in bowl.
Using stand mixer fitted with paddle, mix flour, sugar, baking powder, and salt on low speed, about 30 seconds. With mixer running, add butter, 1 piece at a time, until incorporated and mixture resembles moist crumbs. Add all but 1/2 cup egg mixture and mix until just combined. Increase speed to medium-high and beat until light and fluffy, about 1 minute. Add remaining 1/2 cup egg mixture in slow stream. Scrape down bowl and beat on medium-high speed until well combined, about 15 seconds. Stir in ground sprinkles.
Divide batter evenly among prepared pans and smooth tops with rubber spatula. Bake until toothpick inserted in center comes out clean, 21 to 25 minutes, rotating pans halfway through baking. Let cakes cool in pans on wire rack for 10 minutes. Remove cakes from pans, discarding parchment, and let cool completely on rack, about 2 hours.
Ingredients for the Frosting:
½ teaspoon salt
4 cups (1 pound) confectioners' sugar
Directions for the Frosting:
This recipe makes enough frosting for three 8-inch layers. Using stand mixer fitted with whisk, whip butter, cream, vanilla, and salt on medium-low speed until combined. Slowly add sugar and continue to mix until smooth, about 2 minutes. Increase speed to medium-high and whip frosting until light and fluffy, about 5 minutes.
Place 1 cake layer on plate or pedestal. Spread 3/4 cup frosting evenly over top. Top with second cake layer, then spread 3/4 cup frosting evenly over top. Top with third cake layer, then spread remaining frosting evenly over top and sides. Press remaining 1/4 cup sprinkles around bottom edge of cake. Serve.