1In a large covered soup pot, over low heat, sweat the leeks in butter for 5 minutes.
2Add potatoes and stock, simmer, covered for 20 minutes until potatoes are soft.
3With slotted spoon remove solids and place in food processor, puree, adding the broth or use a handheld puree device.
4Season with salt and pepper.
5Add toppings (optional): crispy bacon, shredded cheddar cheese or sliced scallions
6Serve with sliced baguette.