Heat the oil in a large skillet over medium heat. Add the onion and garlic and cook, stirring occasionally, until the onion is tender, about 5 minutes.
Transfer the onion mixture to a 4-quart or larger slow cooker. Add the beans, ketchup, molasses, brown sugar, Worcestershire sauce, dry mustard, salt, and pepper.
Stir to combine. Cover and cook on low heat for 4 to 5 hours, or until the beans are tender.
Serve hot.
Interesting Facts
Boston baked beans are a traditional dish in New England.
The dish is made from navy beans, which are a small white bean.
The dish was originally cooked in a bean pot in the fireplace.