Cut the bacon crosswise into thin strips. In an appropriately sized pot, melt the butter until it begins to foam. Add the bacon and cook until the bacon is browned and crispy. Set aside. Trim away the green part of the leeks and cut away the root end. Cut in quarters lengthwise and then slice. Place leeks in a bowl and cover with cold water, enough to float the leeks. Add the onion and leeks (remove the leeks from the water with your hands so that any dirt will remain at the bottom of the bowl of water). Cook, stirring occasionally, until they become soft and begin to turn opaque. Add the celery and continue to cook for another 5 minutes. Add the potatoes and garlic. Add the chicken stock and the salt. Bring to a boil, and reduce to a simmer. Cook until potatoes are tender. About 30 to 40 minutes. Add the cheese. Puree in a food processor or with an immersion blender. Season with salt and pepper to taste. Garnish with reserved bacon. Serving ideas: Try serving soup in small espresso cups or decorative shooters as an amuse-bouche before dinner or as a hot appetizer for parties. Use any leftover soup as a sauce under pan-roasted salmon. Notes: This hearty winter soup would pair well with a full-bodied Chardonnay.