Chocolate Sheet Cake with Honey-Roasted Peanut Butter Frosting

A big chocolate sheet cake is one of the friendliest desserts I know: it's unpretentious, easy to transport, feeds a crowd, and most people find it hard to turn down. What takes this particular one over the top though? Crowning it with a light-as-air honey-peanut butter frosting and a sprinkling of honey-roasted peanuts.

Makes 1 (9x13-inch) cake, 12 to 15 servings

For the cake:
Cooking spray or butter
3/4 cup unsweetened natural cocoa powder
1 cup boiling water
2 cups granulated sugar
1 3/4 cups all-purpose flour
1 1/2 teaspoons baking powder
1 1/2 teaspoons baking soda
1 teaspoon fine salt
2 large eggs, at room temperature
1 cup whole or 2% milk
1/2 cup vegetable oil
2 teaspoons vanilla extract

For the frosting:
1 (16-ounce) jar smooth Skippy or Jif honey peanut butter (about 1 1/2 cups), at room temperature
12 tablespoons (1 1/2 sticks) unsalted butter, at room temperature
1/3 to 2/3 cup powdered sugar
1/2 cup honey-roasted peanuts, coarsely chopped (optional)

Make the cake: Arrange a rack in the middle of the oven and heat to 350°F. Generously coat a 9x13-inch baking dish with cooking spray or butter; set aside.

Place the cocoa powder in a medium heatproof bowl. Add the boiling water and whisk until smooth; set aside.

Place the sugar, flour, baking powder, baking soda, and salt in the bowl of a stand mixer fitted with the paddle attachment and whisk to combine. (Alternatively, use an electric hand mixer and large bowl.) Add the eggs, milk, oil, and vanilla. Beat on medium speed until smooth and fluffy, about 2 minutes. Add the cocoa mixture and beat on low speed until just combined, about 1 minute more. The batter will be thin. Transfer the batter to the baking dish.

Bake until a tester inserted in the center of the cake comes out clean, 30 to 40 minutes. Remove the pan to a wire rack and let cool until warm to the touch, about 1 hour. Meanwhile, make the frosting.

Make the frosting: Place the honey peanut butter, butter, and 1/3 cup of the powdered sugar in a clean and dry stand mixer fitted with the paddle attachment. (Alternatively, use an electric hand mixer and large bowl.) Beat on low speed until incorporated. Taste and add more powdered sugar as desired. Increase the speed to medium and beat until fluffy and lightened in color, about 3 minutes.

Spread the frosting onto the barely warm cake and sprinkle with the chopped peanuts if using. Let cool completely, 30 minutes to 1 hour more. Cut into squares and serve.

Recipe Notes

Peanut butter: Can't find honey peanut butter? Just use unsweetened regular peanut butter and add a few tablespoons of honey to taste. I like Skippy Natural, which has an ultra-smooth texture. The smoother the peanut butter, the smoother the frosting.

Storage: Leftovers can be wrapped in plastic wrap and stored at room temperature for up to 3 days.

Making a 6-inch layer cake: To serve 6 to 8 people, you can halve the cake batter recipe. Bake it in 2 (6-inch) round cake pans that are first lined with parchment paper rounds, then greased and floured, at 350°F for 25 to 30 minutes. To just fill the cake and have a thick layer of frosting on top (no frosting on the sides), halve the frosting recipe. To both fill and cover the entire cake, make 2/3 the amount of frosting.