Slice the eggplant, tomatoes, yellow squash, and zucchini in thin rounds. (A mandolin makes the slices uniform and make for quick work.) Put these aside and start the herb seasoning.
2 eggplants, 6 Roma tomatoes, 2 yellow squash, 2 zucchini
Mix all ingredients for the herb seasoning in a small bowl. Set aside and make the sauce.
For the sauce: heat 2 tablespoons of olive oil in pan over medium heat. Sauté the onion and garlic for 1 minute. Add the bell peppers. Cook until soft, about 10 minutes, making sure nothing burns. Once soft stir in the can of crushed tomatoes. Once mixed remove from heat and add the basil.
2 tbsp olive oil, 1 onion, 4 cloves garlic, 1 red bell pepper, 1 yellow bell pepper, salt and pepper, 28 oz crushed tomatoes, 2 tbsp fresh basil, salt and pepper
Assemble the tian: pour sauce into casserole dish. Smooth out the sauce. Arrange the vegetables on their ends in a pattern of your choice on top of the sauce, this can be circular as in the picture provided, or in lines across the casserole. Once arranged, spoon the herb mixture over the vegetables. Cover with aluminum foil and back for 40 minutes. Remove foil and bake for an additional 20 minutes.