01 - Preheat the oven to 350°F. Grease and flour two 8-inch round cake pans
02 - Sift together flour, cocoa powder, baking powder, baking soda, and salt in a large bowl
03 - Whisk mayonnaise, granulated sugar, brown sugar, and vanilla extract in a separate bowl until smooth
04 - Alternate adding dry ingredients and cold water to mayonnaise mixture, starting and ending with dry ingredients. Mix until just combined, avoiding over-mixing
05 - Divide batter evenly between the prepared pans
06 - Bake for 30 to 35 minutes, until a toothpick inserted in the center comes out clean
07 - Let cakes cool in pans for 10 minutes, then turn out onto wire racks to cool completely. Frost and decorate as desired