Chocolate Mayonnaise Cake

Ingredients

For 15 servings

• •Nonstick spray
• •320 g all-purpose flour (11 1/4 ounces; 2 1/2 cups), plus more for dusting
• •60 g unsweetened natural cocoa powder (2 ounces; 3/4 cup)
• •250 g granulated sugar (8 3/4 ounces; 1 1/4 cups)
• •2 c. à café (8g) baking powder
• •1 c. à café (5g) baking soda
• •1 /4 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume
• •300 ml strong black coffee (10 fluid ounces; 1 1/4 cups), at about 170°F (77ºC)
• •300 g mayonnaise (10 1/2 ounces; 1 1/4 cups)
• •1 c. à café vanilla extract
• •200 g unsalted butter (7 ounces; about 14 tablespoons), softened
• •40 g cocoa powder (1 1/2 ounces; 1/2 cup), sifted
• •420 g powdered sugar (15 ounces; 3 3/4 cups), sifted
• •2 c. à soupe (30ml) whole milk or heavy cream
• •1 c. à café vanilla extract

Method

1. 1.For the Cake: Adjust oven rack to middle position and preheat oven to 350°F (175°C). Using nonstick spray, grease a 9- by 13-inch baking pan, then dust with all-purpose flour, shaking out excess.
2. 2.Using a fine-mesh sieve, sift flour and cocoa powder into a large bowl. Add sugar, baking powder, baking soda, and salt and whisk to combine.
3. 3.In another large mixing bowl, whisk coffee, mayonnaise, and vanilla extract until well combined and the mixture resembles foamy, milky coffee, about 20 seconds. Add dry ingredients and whisk until mixture just comes together and no visible dry spots remain, about 30 seconds. (Batter will be slightly lumpy; this is fine. Do not overmix.)
4. 4.Using a flexible rubber spatula, scrape batter into prepared pan. Bake until a cake tester inserted in the center comes out clean and cake pulls away slight from sides of pan, 35 to 38 minutes. Transfer pan to a wire rack and allow cake to cool completely, 1 1/2 to 2 hours.
5. 5.For the Frosting: In the bowl of a stand mixer fitted with the paddle attachment or in a bowl using an electric hand mixer, beat butter on medium-high speed until creamy, about 30 seconds. Add confectioners' sugar and cocoa powder, followed by milk and vanilla extract. Mix on low speed until fully incorporated, then increase speed to medium-high and beat until smooth and fluffy, about 3 minutes more. Using a small offset spatula or flexible rubber spatula, spread frosting over cooled cake. Slice and serve.