This isn’t just any chocolate cake — it’s designed to feed a crowd

Ingredients

For the cake:

• Nonstick spray
• 1 1/2 cups Dutch-process cocoa powder, sifted, plus more for the pans
• 3 cups unbleached all-purpose flour, plus more for the pans
• 3 cups demerara or granulated sugar
• 1 1/2 teaspoons baking powder
• 1 1/2 teaspoons baking soda
• 2 1/2 teaspoons kosher salt
• 4 large eggs plus 2 yolks, room temperature, beaten
• 1 1/2 cups low-fat buttermilk, room temperature
• 1 1/2 cups hot tap water
• 4 teaspoons pure vanilla paste
• 3 tablespoons malted milk powder
• 3/4 cup vegetable oil
• Buttercream frosting (below)
• Milk chocolate and dark chocolate malted milk balls (I like the ones from Whole Foods), lightly crushed, for serving

For the buttercream:

• 2 large eggs plus 2 yolks, room temperature
• 1/2 teaspoon kosher salt
• 3/4 cup granulated sugar
• 1 1/4 cups unsalted butter, room temperature, cut into tablespoon sized pieces
• 7 ounces dark (70%) chocolate, melted and cooled
• 2 teaspoons pure vanilla paste
• 3 tablespoons malted milk powder

Directions

1. For the cake: Heat the oven to 350°F. Generously spray two half sheet trays, line with parchment, and spray again; dust with cocoa powder, tapping out excess. In a large bowl, whisk together the flour, sugar, cocoa, baking powder, baking soda, and salt. Whisk in the eggs, buttermilk, water, vanilla, milk powder, and oil.
2. Divide the batter evenly between the prepared pans. Bake until the tops spring back when lightly pressed, about 30 minutes. Transfer the pans onto a wire rack; let cool 15 minutes. Invert the cakes, remove the parchment, then turn right side up (to prevent sticky tops from sticking to rack); let cool completely.
3. Spread the frosting over top of one cooled cake layer. Top with the remaining layer. Spread a thick coat of frosting over top. Sprinkle with crushed malted milk balls.
4. Do ahead: Unfrosted cake layers can be stored, wrapped in plastic, at room temperature or refrigerated overnight. The frosted cake can be refrigerated overnight.
5. For the buttercream: Beat the eggs and yolks and salt in a stand mixer fitted with a whisk attachment until pale yellow, thick, and ribbony, about 5 minutes.
6. Meanwhile, bring the sugar and 3 tablespoons water to a boil in a saucepan over high heat and cook until the mixture reaches 238°F; remove from the heat.
7. With the mixer on low speed, slowly pour the hot syrup so that it streams down the sides of the bowl, cooling slightly before hitting the egg mixture. When all of the sugar syrup has been added, increase to high speed and beat until light, fluffy, and cool, about 8 minutes.
8. Add butter a piece at a time, beating to incorporate completely before adding another piece and scraping the sides of the bowl often. Gradually add in the chocolate, vanilla, and milk powder, scraping the sides and bottom of the bowl occasionally, until completely incorporated and the frosting is thick, fluffy, and creamy.