Preheat oven to 180 °C.
Place stock in a saucepan and bring to the boil.
Combine stock, chicken, rice and pumpkin in a 6 litre (12 cup) capacity round ovenproof casserole dish and bake, covered, for 45 minutes.
Carefully remove the lid, add peas, tomato and freshly ground black pepper. Toss with a fork, cover and let stand for 5 minutes. Serve with grated cheese.
For a vegetarian option omit the chicken from the recipe.