2 Tablespoons unsalted butter
4 Large leeks, white and tender green parts only, thinly sliced
1 Baking potato (1/2 pound), peeled & cut into 2-inch chunks
5 Cups chicken stock or canned low sodium broth
1 Cup heavy cream
Salt & freshly ground pepper
Chervil or parsley sprigs, (for garnish)
Melt the butter in a large saucepan. Add the leeks and cook over low heat, stirring occasionally, until softened, about 8 minutes. Add potato and chicken stock and bring to a boil. Cover partially and simmer over low heat until the potatoes are tender, about 15 minutes. Add the cream & simmer for 10 minutes longer. Working in batches, puree the soup in a blender, then return it to the pan. Season the soup with salt and pepper, garnish with chervil and serve.