In a cast iron pan, melt 1/2 stick of butter and cover with layer of zucchini. Add in tomato, onion, green pepper. Season with salt and pepper to taste. Cook on low heat until tender.
In a mixing bowl, combine cornmeal, sugar, flour, baking powder, and milk. Stir until well blended.
Spread cornmeal mixture over the zuchinni and vegetables in the pan.
Transfer the pan to a 400 degree F oven and bake for 20 minutes or until cornbread is done.
After bringing it out of the oven, cut into 4 slices and use a spatula to turn the 4 slices over. Top each with 1/4 cup mozzarella cheese.