Melt the butter or margarine in a large saucepan. Add the onions and garlic and sauté for 10 minutes, stirring frequently.
Add the tomato sauce, water, corn, peas, salt and pepper. Cover and cook over low heat for 10 minutes.
Add the potatoes and pumpkin. Cover and cook for 20 minutes, or until the potatoes are tender.
Add the shredded cheese and milk and stir carefully but thoroughly. Cook 5 minutes longer. Serve piping hot.
