Boil and drain the pasta according to package directions for al dente.
Dice the bacon. In a large skillet over medium heat, cook the bacon until crispy. Remove onto a paper towel.
Melt butter in the same pot you boiled the pasta in. Sauté the garlic in the butter until it sizzles. Add the Dijon mustard and stir until bubbly, about 1 minute. Pour in the milk. Whisking constantly, bring to a boil over high heat.
Lower the heat to a simmer and add the cheese, one handful at a time, stirring to combine after each addition. Once all the cheese is added, take the pot off heat. Stir in the bacon bits and al dente pasta.