1 cup unbleached all purpose flour
2 cups sugar
1 cup whole wheat flour
8 tablespoons (1 stick) unsalted butter
? cup unsweetened cocoa powder at room temperature
2 tsp baking powder
? cup olive oil
2 tsp baking soda
3 large eggs, at room temperature
1 tsp fine sea salt
1/3 cup sour cream or yogurt
3 cups grated zucchini
Proceed to Bake as follows:
Position a rack in the center of your oven. Preheat the oven to 350. Butter and lightly flour a 9×13 inch rectangular pan.
Sift the flour, cocoa, baking powder, baking soda, and salt together in a medium bowl. Using an electric mixer on high speed, beat the sugar, butter and oil together in another bowl until well combined.
One at a time, add in the eggs, beating well after each addition. Gradually stir in the flour mixture, blending until just smooth. Stir in the sour cream or yogurt, then the zucchini. Spread evenly in the pan.
Bake until the cake springs back in the center, about 45 minutes. Cool completely over a wire rack.