Preheat the oven to 325°F. grease two cake pans, I sprinkle either a couple of tablespoons of flour or cocoa so the cake comes out easier.
Sift cocoa, flour, baking soda, and baking powder into a small bowl. Add salt and whisk to combine. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, combine egg, vanilla, and sugar. Mix on medium-low for 1 minute, then increase the speed to medium and whip for 5 minutes.
Scrape down the sides of the bowl and mix on medium-high for another 5 minutes.
Add mayonnaise and mix in on medium for 1 minute.
Fold in flour mixture and water in two alternating additions.
Add in the chocolate chips.
Pour batter into prepared cake pans smooth.
Bake 20 to 25 minutes, or until the cake springs back when pressed lightly and a skewer inserted into the center comes out clean.
Let the cake cool completely. Run a knife around the edges of the cake to help get them out of the pans.