Neapolitan Cake

Preparation

1. Cake

   Step 1

   Place racks in upper and lower thirds of oven; preheat to 350°. Lightly coat three 8"-diameter cake pans with nonstick vegetable oil spray, then line bottoms of each with a parchment paper round. Lightly coat parchment with nonstick spray. Pulse one 0.8–1-oz. package freeze-dried strawberries in a spice mill or blender to a fine powder; set strawberry powder aside.

   Step 2

   Whisk 2⅓ cups (292 g) all-purpose flour, 2 cups (400 g) granulated sugar, 1 Tbsp. baking powder, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 1 tsp. baking soda in a large bowl to combine. Add 4 large eggs, 1⅓ cups sour cream, 1⅓ cups vegetable oil, and 1 Tbsp. vanilla extract and whisk until smooth.

   Step 3

   Scoop about 1¾ cups (470 g) batter between 2 additional bowls so you have 3 bowls with an equal amount of batter. Add reserved strawberry powder and a few drops of red or pink liquid or gel food coloring if desired to a bowl and whisk until combined and smooth. Add 2 Tbsp. Dutch-process cocoa powder to another bowl and whisk until combined and smooth. Scrape each bowl of batter into a separate prepared pan and bake cakes until a tester inserted into the centers comes out clean (no need to rotate pans), 25–35 minutes. Transfer pans to wire racks and let cakes cool slightly, about 10 minutes. Run an offset spatula or butter knife around edges of cakes to loosen and turn out onto racks. Carefully peel away parchment. Let cakes cool completely. Using a large serrated knife, trim off mound on top of each cake to create a flat surface if needed.

   Do Ahead: Cakes can be baked 1 day ahead. Store, tightly wrapped, at room temperature.

2. Frosting and Assembly

   Step 4

   While the cakes are cooling, beat 4 cups (440 g) powdered sugar, 2 cups (4 sticks) unsalted butter, room temperature, ¼ cup heavy cream, room temperature, ¼ cup sour cream, room temperature, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 2 tsp. vanilla extract in the bowl of a stand mixer fitted with the paddle attachment, starting on low speed and gradually increasing to high speed as powdered sugar is incorporated, until light and fluffy, about 2 minutes. (If it looks grainy, microwave ¼ cup frosting in a microwave-safe bowl until melted, about 15 seconds, then add back to remaining frosting and beat until smooth. This can happen if your ingredients are not at room temperature.)

   Step 5

   Place strawberry cake layer, right side up, on a cake stand or large plate. Scoop about ¹⁄₃–½ cup frosting on top and spread into an even layer with offset spatula or a spoon. Place vanilla cake layer, upside down, on top. Scoop ¹⁄₃–½ cup frosting on top and spread into an even layer. Place remaining chocolate cake layer, upside down, on top and frost top and sides of all the cakes with remaining frosting. (For a completely smooth look, chill cake 1 hour, then smooth out the sides by dipping offset spatula in hot water, wiping, and running along surface.)