Delicious Duncan Hines Chocolate Mayonnaise Cake

Preheat your oven to 350 degrees Fahrenheit and next grease your 9 x 13 x 2-inch cake pan with cooking spray.
In a large mixing bowl, add the cake mix, eggs, mayo, and water. Mix together by hand or with an electric mixer until the cake batter is well combined.
Using a rubber spatula, fold the chocolate chips into the cake batter.
Pour the cake batter into the 9 x 13 x 2-inch cake pan and bake for 35 minutes or until the center of the cake springs back. Let the cake cool on the wire rack until it is no longer hot and in the meantime make the frosting.
While your chocolate cake is cooling, prepare your chocolate buttercream frosting. In a large or medium mixing bowl, beat the butter with an electric mixer until it becomes creamy. Combine the powdered sugar and cocoa powder in a small and whisk together.
Then, alternate adding in the powdered sugar and cocoa powder with the milk. Beat the frosting mixture until smooth and creamy. Then, mix in your vanilla extract until it is combined.
Using an offset spatula or a rubber spatula, frost your cooled chocolate cake with the chocolate buttercream. Cut the cake with a knife, serve and enjoy.

Instructions