In a 10-inch cast iron skillet, cook the bacon over medium heat until crisp, about 5 to 6 minutes. Remove the bacon with a slotted spoon, and set aside. Reserve bacon fat in pan.
Cook pasta per manufacturer directions.
Whisk flour into the rendered fat. Cook whisking constantly, 2 minutes. Whisk in the milk, salt, mustard, hot sauce and Worcestershire. Bring to a simmer whisking constantly until thickened, almost 15 minutes.
Remove from heat. Add both cheeses and stir until melted and smooth. Stir in bacon, chives and cooked macaroni.
Giangi's Kitchen provides nutritional information, but these figures should be considered estimates, as a registered dietician does not calculate them.