How to Make It
Preheat the oven to 325°. In a large pot, cover the beans with 2 inches of water and bring to a boil. Reduce heat to low and simmer, skimming occasionally, until the skins peel back when you blow on them, about 1 hour. Reserve 4 cups of the cooking liquid and drain the beans.
Transfer the beans to a 10-by-13-inch baking dish. Stick the cloves in a slice of onion; nestle the onion slices, bay leaves and bacon, fat side up, among the beans.
In a bowl, whisk 2 cups of the reserved cooking liquid with the maple syrup, Worcestershire, dry mustard, 1/4 cup of the ketchup and 1 teaspoon of the salt; pour over the beans and bake for 3 hours.
Stir the remaining 1 teaspoon of salt into 1 cup of the cooking liquid; pour over the beans and bake for 1 1/2 hours longer.
Whisk the remaining cooking liquid and ketchup with the Dijon mustard and pour over the beans. Bake for 1 1/2 hours longer, until the beans are richly browned. Let stand for 15 minutes. Discard the cloves and bay leaves, and serve.