Meanwhile, melt butter in separate large saucepan on medium heat. Add flour; cook and stir 2 min. or until hot and bubbly. Gradually stir in milk; cook and stir 3 to 5 min. or until mixture comes to boil and thickens. Stir in mustard. Add cheddar, and 1/4 cup each
Parmesan and bacon; cook and stir 2 to 3 min. or until cheddar is melted.