In a 4 or 5 qt Dutch oven (cast iron preferably) cook the bacon, stirring over medium heat until lightly brown. Add the red onion, celery, and butter and sauté for about 5 minutes or until the onion has softened.
Add the flour and cook, stirring constantly, for about 4 minutes over medium heat. Whisk in the chicken stock and bring to a boil for 1 minute. Reduce the heat and simmer for 15 minutes, stirring occasionally.
Add the milk, slightly warmed, to the soup mixture and simmer for an additional 15 minutes, being careful not to boil once the milk has been added.
Remove from the heat and stir in cheese, Tabasco sauce and Worcestershire sauce, salt and pepper until the cheese is melted and the soup is smooth. Stir in warm beer. If the soup is too thick, thin with some warm milk.
Serve soup hot and garnish with the chopped chives or scallions.