Clean, wash and chop the peppers, zucchini and tomatoes. Clean, wash and halve the mushrooms. Peel onion and garlic, chop roughly. Wash, pluck and chop rosemary and thyme.
Mix all the vegetables, mushrooms, onions, garlic and herbs with the oil on a baking tray. Season vigorously with salt and pepper. In a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) at least
Bake for 40 minutes. Stir after about 15 minutes and add olives. Season ratatouille again with salt and pepper. A thyme-garlic cream tastes good with it.