Candy Corn Cake

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. Whisk flour, baking soda, baking powder, and salt together in bowl. In second bowl, whisk boiling water, chocolate, cocoa, and espresso powder until smooth.

Using stand mixer fitted with paddle, beat butter and sugar on medium-high speed until pale and fluffy, about 3 minutes. Add eggs, one at a time, and beat until combined. Add sour cream, vanilla, and black food coloring and beat until incorporated.

Reduce speed to low and add flour mixture in 3 additions, alternating with chocolate mixture in 2 additions, scraping down bowl as needed. Give batter final stir by hand.

Divide batter evenly among prepared pans and smooth tops with rubber spatula. Bake until toothpick inserted in center comes out clean, about 20 minutes. Let cakes cool in pans on wire rack for 15 minutes. Run knife around edges of pans. Remove cakes from pans, discarding parchment, and let cool completely on rack, at least 1 hour.

FOR THE FROSTING: Using stand mixer fitted with whisk attachment, whip butter and salt on medium speed until smooth, about 1 minute. Reduce speed to low and slowly add sugar. Increase speed to medium and whip until smooth, about 2 minutes, scraping down bowl as needed. Add marshmallow crème, increase speed to medium-high, and whip until light and fluffy, about 5 minutes. (Frosting can be refrigerated for up to 24 hours. Let sit at room temperature until softened, about 1 hour, and whip in stand mixer until light and fluffy before using.)

Transfer 1⅓ cups frosting to each of 2 small bowls. Add orange and red food coloring to first bowl and yellow food coloring to second bowl, stirring well to combine. Set aside remaining white frosting.

Place 1 cake layer on cake turntable. Spread 1 cup yellow frosting evenly over top, right to edge of cake. Top with second cake layer, press lightly to adhere, then spread 1 cup orange frosting over top, right to edge of cake. Top with remaining cake layer, pressing lightly to adhere. Spread 1½ cups white frosting evenly over top and sides of cake. Refrigerate cake for 30 minutes.

Using offset spatula, spread remaining ⅓ cup yellow frosting over bottom third of sides of cake. Spread remaining ⅓ cup orange frosting over middle third of sides of cake. Spread ⅓ cup white frosting over top third of sides of cake. While spinning cake turntable, run edge of offset spatula around cake to blend colors and smooth sides of cake.

Arrange candy corn around top edge of cake, alternating orientation of white side and yellow side. Fill pastry bag fitted with ½-inch-wide straight tip with remaining 1¼ cups white frosting and pipe dots inside ring of candy corn. Refrigerate until frosting is firm, at least 30 minutes. Serve.