In a large pot brown bacon. Remove from pan, and drain on a paper towel. Remove bacon drippings, leaving about 1 Tbls in the pan. Add onion, celery, carrots, and garlic, saute until soft. Do not brown the veggies. Add flour and butter, stirring until the flour is cooked. Whisk in chicken stock, and beer. Add back in about 1/2 of the bacon, what is left will be used for garnish when serving. Using an immersion blender, blend until smooth. If you don't have an immersion blender you can use a food processor or regular blender. Bring the soup to a boil. Once boiling, over a medium heat gradually add cheese, and mix until smooth. Add the cream and dry mustard, whisk until combined and heated through. Serve garnished with bacon.