1Melt the butter in a large heavy pot over low heat. Add the onion,leek,celery and carrots and cook,covered until the vegetables are tender and lightly colored, about 25 minutes,stirring occasionally.
2Add the potato,white wine, and stock, bring to a boil,reduce the heat and simmer partially covered until very tender about 20 minutes.
3Remove the soup from the heat and crumble in 1/2 pound of the cheese. Stir until the cheese has melted into the soup, then pour the soup through a strainer, reserving the liquid. Transfer the solid to a food processor or use a food mill fitted with a medium disc. Add 1 cup of the cooking stock and process until smooth.
4Return the soup to the pot, pour in the rest of the liquid and simmer over medium heat. Taste and correct the seasoning; you may want to add a little more cheese, and the soup may need salt and pepper.
5Ladle into bowls, garnish with the bacon crumbles and serve immediately.