Preheat the oven to 180°C (350°F). Place the chicken pieces in a large baking dish. Add the sliced mushrooms, cubed potatoes, chopped tomatoes, onions, carrots, green peppers, and garlic cloves.
In a small bowl, mix together the tomato paste, olive oil, black pepper, thyme, and salt until well combined.
Pour the sauce over the chicken and vegetables. Toss everything together until all the ingredients are evenly coated.
Cover the baking dish with aluminum foil and bake for 1 hour, stirring once or twice during cooking to ensure even roasting. Remove the foil during the last 15 minutes if you'd like a lightly browned top.
Sprinkle the grated cheddar cheese evenly over the dish. Return it to the oven and bake for another 5 minutes, or until the cheese is melted and lightly golden.
Serve hot as a hearty main dish with rice, bulgur pilaf, or fresh crusty bread.
