Preheat your oven to 200°C (400°F) and line a large sheet pan with parchment paper.
Wash and slice the eggplant into 1/2-inch thick rounds or chunks, then do the same for zucchini, bell peppers, and tomatoes. Aim for uniform slices so everything cooks evenly.
In a mixing bowl, toss all the sliced vegetables with 2 tablespoons of olive oil, minced garlic, salt, and chopped fresh herbs. Make sure each piece is nicely coated with the oil and seasonings.
Spread the seasoned vegetables evenly on the prepared sheet pan in a single layer, giving each piece space to roast without overlapping too much.
Bake in the oven for 25 to 30 minutes, shaking the pan halfway through. The vegetables should be tender and edges slightly caramelized, with a fragrant aroma filling the kitchen.
Once done, remove the pan from the oven and let the vegetables rest for a few minutes. If desired, drizzle with a little more olive oil and sprinkle with extra fresh herbs for added flavor and color.
Serve the sheet pan ratatouille warm, accompanied by crusty bread or as a hearty side dish. The vegetables will be tender, slightly caramelized, and bursting with flavor.