Wash the chicken breasts, pat dry, pepper and place in the baking dish. Wash and clean vegetables. Cut the bell pepper and zucchini into bite-sized pieces, cut the spring onion into rings. Finely chop the garlic.
Mix the vegetables together and place on and around the chicken breast. Mix the tomatoes, tomato paste, harissa paste and spices and pour over the chicken and vegetable mixture. Sprinkle the grated cheese on top and cook for about 35 minutes at 180 degrees in the oven (top and bottom heat).