1. Rinse the head of garlic to remove any outside grit or dirt. Cut the top third off the head and peel any loose papery skins off the bottom two-thirds. Pop out garlic heads and mince; reserve bottom two-thirds whole.

2. In a large, heavy pot or Dutch oven, melt the butter over medium heat. Add leeks and cook them until soft (but not brown), about 5 minutes. Add the minced garlic heads and cook another minute. Add the larger part of the garlic head (whole, not chopped), broth, bay leaves and 3/4 teaspoon salt. Reduce heat and simmer until garlic is very tender when pierced with tip of knife, 30 to 40 minutes. Add potatoes and continue to simmer, partially covered, until potatoes are tender, about 15 to 20 minutes.

3. Discard bay leaves. Remove garlic heads. Optional: If you’d like an extra garlic boost to the soup, using tongs or paper towels, squeeze garlic head at root end until cloves slip out of their skins. Using a fork, mash the garlic cloves to smooth paste and add it back to the soup.

4. Add greek yogurt to soup and cook for another 2 to 3 minutes. Adjust seasonings, adding more salt and pepper to taste. Using immersion blender, process soup until chunky-creamy, leaving lots of potato texture intact. (Alternatively, transfer a portion of the potatoes and broth to a food processor or blender and puree until smooth.) Serve with whatever makes you happy on top, or nothing at all.