Layer bottom of casserole dish with sliced zucchini, then put a layer of fresh tomatoes sliced (same amount as zucchini). Peel tomatoes if hulls are tough. Place rings of fresh sweet onion on top of tomatoes. Sprinkle with salt, pepper and basil or whatever spices you wish to add. Sprinkle tablespoon or so of brown sugar on tomatoes also. Put a layer of cracker crumbs over this and dot with butter. Then sprinkle with 1/2 cup or so of grated cheese. Bake at 350 degrees for 35 minutes covered. Then remove cover and bake another 30 minutes or so until zucchini is done to taste. May have to adjust cooking time according to size of dish prepared. Watch cheese topping to see that it doesn't get too brown. (A simple, good summer vegetable dish! Does not freeze well.)