Preheat your oven to 400°F (200°C). Wash and chop all the vegetables into large, uniform, rustic pieces to ensure they hold their shape perfectly during baking.

In a large, deep metal roasting pan, combine the chunks of eggplant, zucchini, bell peppers, onion wedges, whole button mushrooms, whole cherry tomatoes, and smashed garlic. Pour the canned crushed tomatoes over the top. Drizzle with the first 1/4 cup of extra virgin olive oil. Sprinkle the dried oregano, sea salt, and black pepper evenly over everything. Toss thoroughly with your hands or large spoons until every piece is uniformly coated.

Spread the vegetable mixture out into an even layer in the pan. Place uncovered into the preheated oven and bake for 40 minutes, allowing the vegetables to soften and release their natural juices.

Carefully remove the pan from the oven. Use a large spoon to gently stir and flip the vegetables. Drizzle the remaining 1/4 cup of extra virgin olive oil evenly over the surface. Return the roasting pan to the oven for another 25 to 30 minutes, removing it when the vegetable edges are beautifully charred and the tomato sauce has reduced into a thick, glossy glaze.

Allow the ratatouille to rest on the counter for 10 minutes before serving. Garnish with torn fresh basil or chopped parsley if desired, and serve hot or warm alongside plenty of crusty artisanal bread.