In a large pot, blend the olive oil, rice, chicken or veal pieces, tomatoes, garlic, onion, saffron, parsley, salt and pepper. Cook for 15 minutes, stirring occasionally.
Place in a casserole and add the chicken stock. Cover and bake slowly in a 325 degree oven for 35 to 40 minutes, or until the rice has absorbed the stock. Blend in the peas and mushrooms and cook for an additional seven minutes.