Mayonnaise may sound odd in a cake, but trust me, it's the secret to a delightfully moist and fluffy texture. It prevents the cake from drying out, without any complex baking techniques.
Evenly divide batter into two greased cake pans and tap to remove air bubbles. Bake for 20-22 minutes or until toothpick comes out clean. Cool cakes in pan for 10 minutes, then transfer to wire racks to cool completely before frosting. Can be prepared a day in advance.
Sift cocoa powder and powdered sugar. Add softened butter, milk, vanilla extract, and salt. Use electric mixer to fully combine and set aside. Frost cooled cake and enjoy!