First you have to have good marinara sauce. The sauce that is most similar to my mother's and mine is Giada's marinara sauce. The only different thing I do is I add roughly 1/2 tsp. dried basil to the recipe. I make a large amount of marinara, and I freeze it, or use it up in different meals throughout the week. So make your spaghetti dinner the night before, and reserve some leftover marinara for this recipe. You'll need at least a couple cups, maybe 3 cups.
Preheat oven to 400 degrees
One medium large eggplant sliced thinly, around 1/4 inch thick, and cut the rounds in half.
4 medium zucchini sliced into ovals, also 1/4 inch thick.
2 large bell peppers (one green, one red, as round or square as possible) I cut the cheeks off the peppers, then cut each cheek into 3-4 large pieces
Half of a medium onion, cut in half again, so you don't have rings. Separate the layers
Herbs de Provence
Dried garlic or 2 cloves fresh, chopped
Salt & Pepper
Optional: You can also add sliced cauliflower like my mom does, or 1-2 medium potatoes sliced 1/4 inch thick, or also sliced yellow squash, to add to the color spectrum.
Optional: shredded mozzarella cheese
In a 9x13 baking dish, add enough marinara to cover the bottom at least 1/2 inch. Start layering your veggies like they did in the movie "Ratatouille". You might not be able to repeat all the layers with the onion. What I did was just shove pieces of onion between layers here and there after it was all assembled. And mine isn't as pretty as the cartoon, because my veggies are odd shapes, but it's rustic and beautiful as it is. If you have extra veggies lying around, shove as many as you can into the layers, no one can tell they're not in perfect order. Then sprinkle on around 1 tsp. of course sea salt, a few cracks of fresh ground pepper all around the casserole, then around 1 (or more) tsp. of Herbs de Provence, and 1 tsp. dried, diced garlic, or more if using fresh garlic. Drizzle with olive oil on top. Then cover with aluminum foil. Bake for one hour.
Remove foil and sprinkle with mozzarella cheese. Return to the oven for another 15 or so minutes to melt the cheese. You can omit the cheese to keep it vegan. While this is baking, cook up your favorite brown rice, and add a dollop to the bottom of the bowl when serving. This makes it so hearty and fulfilling. Such a simple recipe, and such a simple pleasure.