Preheat oven to 350 degrees F (175 degrees C). Grease a 2-quart casserole dish.
In a large bowl mix together the zucchini, onion, eggs, muffin mix, salt, and pepper. Stir in 4 ounces of the cheese. Spread this mixture into greased 2-quart casserole dish; top with remaining 4 ounces of cheese.