In a medium-sized cast-iron pan, cook diced bacon over medium heat until crispy. Remove bacon, discard the fat, and set aside.
In the same pan over medium heat, add flour and unsalted butter. Whisk to combine and continue stirring frequently for three minutes until the roux is activated.
Pour in the beer, stirring, and let it simmer for 2 minutes. Stir often and adjust the heat for a gentle simmer. After 2 minutes, add the milk and continue simmering for an additional 2 minutes.
Reduce the heat to low and add cream cheese and shredded cheeses. Stir until melted and combined, approximately 2 minutes.
Incorporate Dijon mustard, Worcestershire sauce, and chopped chives. Stir well.
Sprinkle the reserved bacon over the cheese sauce. Serve immediately or transfer to a fondue or warming pot to keep it warm and melted. Enjoy the dip with fresh pretzels, corn chips, or grilled sausage.