1. Drain beans and discard soaking liquid, then transfer to a large pot and add enough water to cover by 3". Cut dark leaves from leek and add to pot, then thinly slice light green part and set aside. Add celery, 2 tablespoons oil, the halved head of garlic, thyme, and 2 teaspoons salt, then bring to a boil over high.
2. Reduce heat to medium-low and simmer, stirring occasionally, until tender and creamy, 20 to 30 minutes for navy beans and 40 to 60 for cannellini or Great Northern beans. Set a strainer over a large bowl. Discard leek greens, celery, garlic, and thyme, then strain beans, reserving liquid. Wipe out pot.
3. Heat remaining 1/4 cup oil in pot over medium until shimmering. Add reserved leek slices, season with salt and pepper, and cook, stirring occasionally, until tender, about 5 minutes.
4. Stir in sliced garlic clove and cook until fragrant, then add beans and 3 cups reserved cooking liquid (discard remaining liquid or save for another use). Cook, stirring occasionally, until flavors meld, about 5 minutes, then season with salt and pepper to taste. Divide among bowls and drizzle with more oil, then sprinkle evenly with lemon zest and herbs. Serve with grated cheese.
Source: Hannaford fresh Magazine, March-April 2021