Step 1

Preheat oven to 350º F. Spray or grease a 13x9 inch pan. Set aside.

Step 2

In a large bowl mix together butter, oil, sugar, vanilla, baking soda, baking powder, and salt until well combined and smooth.

Step 3

Add the eggs and beat until fully incorporated.

Step 4

Mix in the yogurt and flour, alternating between the two.

Step 5

Add the cocoa powder and mix until the batter is smooth.

Step 6

Fold in zucchini and chocolate chips until evenly combined.

Step 7

Pour into the prepared baking pan. Bake for 35-40 minutes, until a tester comes out clean. Remove from the oven and cool completely.

Step 8

To prepare the frosting mix together all of the ingredients until smooth, and desired consistency. Add additional milk or sugar if necessary.

Step 9

Once the cake is completely cool; spread frosting over the cake.