Step 1

The night before - soak: Add beans to a large bowl and fill with water. (Beans can triple in size so make sure there's plenty of water). Cover and let soak at room temperature overnight.

Step 2

The next day - drain and preheat: Drain and rinse soaked beans. Transfer beans to a large Dutch oven. Position a rack so that the Dutch oven (with the lid on) will be roughly centered in the oven. Preheat oven to 375°F (190°C).

Step 3

Combine and bake: Trim the tops (about ½-inch / 1 cm) off each head of garlic to reveal the cloves. Add the heads of garlic, onion, shallots, broth, olive oil, tomato paste, thyme, bay leaves, salt, pepper, and red pepper flakes to the pot. Stir to mix. Cover with a lid. Bake until beans are tender, 1 hr 45 minutes to 2 hours.

Step 4

Finish seasoning: Use a slotted spoon (or tongs) to press the heads of garlic against the side of the pot to release the soft garlic cloves. Remove and discard the garlic skins, bay leaves, and thyme sprigs. Stir well to mix the garlic into the broth. Taste and season with more salt and pepper. Ladle beans and broth into bowls. (See note 2 for serving suggestions).