Grease oval baking dish, about 10 inches across, or an 11X9 inch glass baking dish.
Layer onions at the bottom of prepared baking dish. Sprinkle with garlic slices. Pour crushed tomatoes over onions and garlic.
Layer vegetables vertically over sauce, filling the dish. Drizzle vegetables with olive oil. Sprinkle with salt, pepper, and italian seasoning. Cut a piece of parchment paper to fit over vegetables. Place parchment over vegetables, and bake 45-55 minutes or until vegetables are soft. Top with mozzarella and basil for serving.
Instant Pot Directions
Layer onions at the bottom of the instant pot insert. Sprinkle with garlic slices. Pour crushed tomatoes over onions and garlic.
Layer vegetables vertically over sauce, filling the dish. Drizzle vegetables with olive oil. Sprinkle with salt, pepper, and italian seasoning.
Seal Instant Pot. Set vent to sealed. Program for "manual" and "high pressure" and set timer for 5 minutes.
After it's done, allow natural release (takes 10-15 minutes). Open instant pot, layer fresh mozzarella over vegetables, and sprinkle with fresh basil ribbons.