1Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.
2Combine biscuit mix, Parmesan cheese, mozzarella cheese, parsley, oregano, basil, and salt in a bowl. Mix eggs, oil, and onion in a bowl. Stir biscuit mixture into egg mixture until just combined; fold in zucchini and pepperoni. Transfer to baking dish.
3Bake in preheated oven until golden brown and set, 30 to 35 minutes. Allow to cool slightly and cut into squares.