Pre-heat oven to 375 degrees F.
Bring a large pot of generously salted water to a boil.
Add pasta and cook for 8 to 10 minutes or until firm, then drain.
In a large sauce pan over medium heat, melt 2 tablespoons of butter. Whisk in flour and cook, stirring to make a roux.
Adding just a little at a time, whisk in the milk, mustard, salt, pepper & your hot sauce.
Boil 1 minute, then remove from heat and whisk in the cheeses until smooth.
Stir in cooked pasta & the sausage cubes and pour into shallow 2 quart baking dish.
Melt remaining 2 tablespoons of butter. Stir in the bread crumbs with a little salt and pepper. Sprinkle over the macaroni mixture.
Bake 30 minutes until bubble and golden. Let stand 10 minutes before serving.