1. Preheat oven to 325°
2. Spray a 9×13 baking dish with cooking spray and set aside.
3. In bowl of stand mixer beat butter, vegetable oil and sugar together until smooth. Add in vanilla, baking soda, baking powder, salt and eggs and continue mixing until smooth and combined, scraping sides as needed.
4. Add in sour cream alternately with the flour, mixing after each addition until smooth.
5. Next mix in cocoa powder until evenly combined.
6. Finally fold in zucchini and chocolate chips.
7. Pour batter into prepared pan and bake for 30-40 minutes or until a toothpick inserted in center comes out clean.

Frosting

1. In a medium saucepan over medium-low heat melt butter, milk, and cocoa powder together, stirring frequently. Remove from heat and whisk in powdered sugar until there are no more lumps.
2. Pour frosting over your cake while it’s still warm.
3. Allow the cake to cool completely before serving.