Preheat the oven for 375˚F.

Heat the olive oil in a large skillet over medium-high heat.

Sauté the onion, garlic, and bell peppers until soft, about 10 minutes.

Season with salt and pepper, then add about 1/3 of the sliced tomatoes. Cook until the tomatoes have cooked down, adding olive oil to the pan as needed.

Once everything is fully incorporated.

Remove from heat, stir in the basil, and transfer the cooked vegetables into the bottom of a casserole pan.

Smooth out the surface evenly with a spatula.

On top of the cooked vegetables start arranging the sliced veggies in alternating patterns.

Line the outline of the casserole pan with eggplant, then start layering upright the rest of the vegetables.

Line up, eggplant, tomato, zucchini and repeat starting from one end of the casserole dish to the other.

Season with salt and pepper and set aside.

In a small bowl, make the Herbed Oil Seasoning by mixing together the basil, garlic, parsley, thyme, salt, pepper, and olive oil.

Poor the herb seasoning over the ratatoullie.

Cover the pan with foil and bake for 40 minutes.

Carefully uncover the dish, then bake for another 20 minutes, until the vegetables are softened.

Serve with freshly grated parmigiana cheese!