Preheat your oven to 375°F (190°C).

Slice the eggplant, zucchini, yellow squash, and tomatoes into 1/4-inch rounds.

Dice the onion and bell pepper. Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the onion and bell pepper, cooking until softened, about 5-7 minutes.

Add the minced garlic to the skillet and cook for another minute until fragrant. Then pour in the crushed tomatoes. Season with salt, pepper, and half of your fresh herbs. Simmer this sauce for 10 minutes, stirring occasionally.

Spread the tomato sauce evenly across the bottom of a 9x13-inch baking dish.

Arrange the sliced vegetables in alternating patterns standing upright in the dish.

Drizzle the remaining olive oil over the arranged vegetables. Season generously with salt and pepper. Sprinkle the remaining fresh herbs on top. If using cheese, add it now.

Cover the Ratatouille Casserole tightly with aluminum foil. Bake for 40 minutes. Then remove the foil and bake for an additional 20-25 minutes until the vegetables are tender and lightly browned on top.

Let the casserole rest for 10 minutes before serving.