Mix together onion, ketchup, molasses, brown sugar, mustard, and Worcestershire sauce. Add beans and stir to blend.
Turn mixture into a 2 quart casserole and bake at 300°F for 1 hour.
Arrange franks on the beans; bake 30 minutes longer.
Dietary adaptations Worcestershire sauce can contain soy sauce, which is not gluten-free, and some baked beans may have flavorings that are not GF. Verify that both your Worcestershire sauce and your canned beans are free of wheat ingredients. Worcestershire sauce is also typically not vegetarian, but The Wizard's™ Organic Gluten Free Vegan Worcestershire (affiliate link) is, and it's also GF (obviously).