Chocolate Mayonnaise Cake

Preheat your oven to 350°F (175°C). Prepare a 9x13-inch cake pan by spraying it with non-stick cooking spray.
In a large mixing bowl, combine ¾ cup mayonnaise, 1 ¼ cups warm coffee, 2 eggs, and 2 teaspoons vanilla extract. Whisk together until smooth.
In another bowl, whisk together 2 cups all-purpose flour, 1 ½ cups granulated sugar, ¾ cup cocoa powder, 2 teaspoons baking soda, ½ teaspoon baking powder, and 1 teaspoon salt.
Gradually add the dry ingredients into the wet ingredients. Whisk gently until fully combined.
Pour the batter into the prepared cake pan and bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean. The cake should spring back lightly when pressed.
Let the cake cool completely before frosting.
For the frosting, beat 1 cup softened butter in a stand mixer until fluffy. Add 3 cups powdered sugar, and beat on low speed until incorporated, then increase speed to fully combine.
Scrape the sides and bottom of the bowl, and add ½ cup cocoa powder, 3 tablespoons milk, 1 teaspoon vanilla extract, and ¼ teaspoon salt. Beat on medium-high until smooth and creamy. If too thick, add more milk, one tablespoon at a time.
Once the cake has cooled, apply the frosting by dolloping spoonfuls across the surface and spreading it evenly. It's best to chill the cake for an hour before frosting to ensure the frosting sets better.