Cook the bacon slices until crispy. Remove bacon to a paper towel-lined plate to absorb excess grease. Using a mesh sieve, strain the bacon grease in the pan to remove the big chunks and any burnt pieces. Reserve at least 3 Tbsp of the bacon grease.
Preheat your oven to 325 degrees and lightly butter a glass or ceramic 13×9” baking dish.
Start the cheese sauce. Melt 1/2 cup of butter to a large skillet (with high sides) over medium heat. Once melted, add the bacon grease and stir well to incorporate.
Add the flour and stir constantly to cook the flour, about 2 minutes. Slowly add the milk, whisking constantly to ensure a smooth sauce.
Begin cooking your pasta.
Add the salt, pepper and ground mustard. Whisk well to incorporate. Bring the cream sauce to a boil and then lower heat to low until the sauce has thickened, about 3-4 minutes. The cream sauce should be thick enough to coat the back of a spoon.
Remove the skillet from heat and stir in the 6 cups of cheese. Stir well until the cheese is completely melted. If it does not melt completely, add it back to low heat until the cheese has melted.
Chop up the cooked bacon pieces. Add 1/3- 1/2 of the chopped bacon pieces to the cheese sauce. Reserve the rest of the chopped bacon for the topping.
Drain your cooked pasta. Add the pasta back tothe large pasta pot. Pour bacon-cheese sauce over pasta and stir well to coat all of the pasta.
Pour the pasta into the prepared dish. Top with about 1/2 cup more freshly shredded cheese. Begin cooking your topping.
Add the 5 tbsp of butter to a medium skillet. Once the butter is melted, add the Panko breadcrumbs. Stir constantly until the breadcrumbs are toasted, about 3-4 minutes. Be careful not to burn.
Stir the toasted breadcrumbs with the reserved chopped bacon. Evenly spread the bacon-Panko mixture over the top of the Mac and cheese.
Bake in a preheated oven until nice and bubbly and hot, about 25 minutes. Enjoy as a main dish or a side.
