Pre-heat oven to 425o F. In a pot of boiling salted water, cook the pasta until al dente; drain.

In an extra-large oven-proof skillet set over medium-high heat, melt the butter. Whisk in the flour and cook, whisking constantly, until the paste cooks and bubbles a bit, about 2 minutes. Add 3 cups of the hot milk and cook, whisking constantly, until the sauce thickens, about 5 minutes. Season to taste with salt and pepper. Bring the sauce to a boil, reduce the heat to low, and cook, stirring, for 2 to 3 more minutes. Stir in the dry mustard and cayenne pepper, and then gradually add the Borden® Sharp Cheddar Thick Cut Shreds, stirring constantly until all of the cheese has melted into the sauce. Stir in the remaining 1 cup milk. Add the cooked pasta to the sauce and stir to coat. Season to taste with salt and pepper.

Coat the breadcrumbs with reserved bacon fat and sprinkle the mixture over the top of the skillet. Sprinkle the top with 1/2 cup Borden® Parmesan Shreds.

Bake until the top is browned, and the sauce is bubbling, 10 to 12 minutes. Top with crumbled cooked bacon. Garnish with parsley and let sit 5 minutes before serving.