2 medium eggplant, sliced ¼-inch thick
3 medium zucchini and/or yellow squash, sliced ¼-inch thick
2 tablespoons butter
1--2 bell peppers, any color, seeded and chopped
1 medium onion, chopped or 1 cup sliced leeks
2 tablespoons flour
3 cups chopped tomato, see note
12 saltine crackers, crumbled
2 cups grated mozzarella cheese
1 teaspoon dried oregano
Heat oven to 350 degrees. Butter a 9-by-13-inch baking pan.
Arrange eggplant slices in a single layer on rimmed baking sheets. Sprinkle both sides of each slice lightly with salt and allow to sit at room temperature for about 1 hour. Salting draws out the liquid and bitter flavor. After an hour, rinse with cold water and dry slices thoroughly before adding to casserole. (This step is optional and may be skipped if time is limited.)
Heat about 1 inch of water to a boil in large skillet. Place zucchini slices in boiling water for about 5 minutes, or until slightly softened; drain on paper towels.
Wipe skillet dry and add butter. Once melted, add peppers and onions and sauté 5 minutes, or until slightly softened. Add flour, stirring to thoroughly combine. Mixture will be thick and should have no flour lumps. Add tomatoes and cook until thick and bubbly, stirring constantly.
Place zucchini in a single layer on the bottom of the buttered pan; top with dried eggplant. Spread tomato mixture over eggplant evenly and sprinkle with crumbled saltines. Top with mozzarella cheese and sprinkle with oregano. Bake uncovered 30 minutes or until bubbly.
Cook's note: Blanching and peeling the tomatoes is preferred, but not required.