Preheat the oven to 200°C.
Dice paprika peppers, halve zucchini lengthwise and cut them into slices of about 1cm in thickness. Halve onion and cut into thin slices. Heat oil in a pan, spice chicken with salt and pepper and fry them all around. Remove chicken and fry paprika cubes, zucchini and onion for some minutes stirring regularly. Add crushed garlic and tomatoes, seson to taste with salt, pepper and rosemary. Pour the ratatouille into a gratin or roasting tin, add chicken and bake it for 25 minutes.