This is a moist, amazing take on brownies. Check the comments for the full recipe ~~

brownie cake:
15.25 ounces chocolate cake mix (Any chocolate cake mix should do. I always use Betty Crocker – it has pudding in the mix. I used Triple Chocolate Chunk variety for this.)
18.3 ounces fudge brownie mix
4 large eggs
1¼ cups water
1 cup vegetable oil, or canola oil
½ cup mayonnaise
1 cup chocolate chips