Chocolate Cake with Malted Chocolate Ganache and Toasted Marshmallow Frosting

Preheat oven to 325 degrees. Spray two 9-inch round cake pans with nonstick cooking spray. Line bottom of each pan with a parchment paper round and spray again; set aside.

In the bowl of an electric mixer fitted with paddle attachment, cream together butter and sugar on medium speed until light and fluffy, 5 to 8 minutes. Add cocoa powder and beat until combined, 3 to 5 minutes more, scraping down the sides as necessary.

In a small bowl, whisk together eggs and egg yolk. With the mixer on low, slowly add eggs, mixing until smooth and well combined, scraping down sides of the bowl as necessary.

In a large bowl, sift together both flours, salt, baking powder, and baking soda. Add to butter mixture and mix on low speed until combined.

In a medium bowl, mix together boiling water and oil. With the mixer on low, slowly add water mixture and mix until combined. Divide mixture evenly between prepared cake pans. Transfer to oven and bake until a cake tester inserted into the center comes out clean, 35 to 40 minutes.

Transfer cakes to wire racks; let cool completely, at least 2 hours. Unmold cakes and remove parchment paper. Using a serrated knife, trim tops of cakes to make level, then cut each cake in half horizontally. Place four strips of parchment paper around perimeter of a serving plate or lazy Susan. Place the bottom side of one bottom half on the cake plate. Evenly spread top with one-third of the ganache. Repeat process twice with top halves of each cake and top with the remaining bottom half of cake bottom-side up. You should have three layers of ganache and four layers of cake.

Transfer marshmallow frosting to a pastry bag fitted with a plain 5/8-inch round tip (such as Ateco #808). Pipe frosting over cake to cover; evenly spread using an offset spatula. Using a kitchen torch, toast frosting until lightly browned.