Combine Gruyere cheese and flour in large bowl. Simmer wine and garlic in heavy medium saucepan or fondue pot 1 minute. Reduce heat to medium-low. Add Gruyere cheese mixture to saucepan 1 handful at a time, stirring constantly until cheese melts before adding another handful. Whisk in Roquefort cheese (mixture will look grainy). Whisk in mustard. Boil until smooth and thick, stirring constantly, about 2 minutes. Place pot over canned heat burner to keep warm. Serve with potatoes, bread and/or sausages. l I