Preheat the oven to 350 F.

In a large bowl, sift together the flour, cocoa, espresso powder, baking soda and salt and set aside.

In another bowl, add the sugar, brown sugar, yogurt, oil and vanilla and mix together until nice and smooth. 

Add the sugar mixture to the flour mixture and combine until smooth. 

Stir in the zucchini.

Pour zucchini brownie mixture evenly into a greased 13×9 pan. Sprinkle chocolate chips over the top. Bake at 350 F for 35-40 minutes or until a toothpick inserted into the center of the brownies comes out clean. 

Cool before slicing.