Preheat oven to 400 degrees. Boil and drain the pasta.

In a large skillet, cook the bacon. Once it cools, dice it up and set it aside.

In the same pot you boiled the pasta in, saute the garlic in the butter until it sizzles. Add the Dijon mustard and saute until bubbly, about 1 minute. Pour in the milk. Whisking constantly, bring to a boil.

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 most of the bacon (leave some to sprinkle on top) and pasta. Transfer to a 9×13 baking dish. Bake for 10 minutes or until top has a golden crust and is bubbly.

Remove from oven, garnish with the reserved bacon and chives.