Texas Baked Beans recipe

1/4 cup butter
2 onions, chopped
1 pound hamburger
1 (31 ounce) can pork and beans
2 (15 ounce) cans Ranch style beans
1/4 cup prepared mustard
1 cup brown sugar
1/4 cup maple syrup
1 cup ketchup

Sauté onions in butter. Add meat and cook until brown. Pour off the fat. Mix all the ingredients in a casserole dish. Bake, uncovered, at 300 degrees F for two hours.