Mom's new england fish chowder

1. Cook the potatoes and onion in water to cover until almost done.
2. Add fish which has been cut into small pieces and cook slowly until potatoes are done.
3. Do not overcook the fish.
4. Add one 12 ounce and one 5 ounce can of condensed milk and continue to simmer until everything is heated.
5. Add butter, salt and pepper to taste and serve with fresh baked muffins.