Preheat the oven to 325 degrees.
Grease a 9 x 13" casserole dish.
In a stand mixer or in a large bowl, beat together the butter, oil, and sugar.
Add in the egg and the vanilla beat until combined.
Stir in the sour cream.
Sift the flour, baking soda, salt, and unsweetened cocoa powder together in a separate bowl. Add to the wet ingredients and stir to combine.
Fold in the zucchini using a rubber spatula.
Spread the brownie mixture into the greased pan with the rubber spatula. Sprinkle the chocolate chips on top.
Bake in the oven for 45-50 minutes, or until a toothpick comes out clean.