Preheat oven to 375 degrees.

In a large pot, bring to boil salted water and add macaroni. Bring to a boil again and cook till al dente (about four minutes). Then, drain in a colander, rinse with cold water to stop the cooking, and set aside.

Grease a 2.5 quart casserole dish (or 9x13 baking dish) with the stick of butter, wiping all sides of the dish with the stick.

Start making the cheese sauce. Over medium heat, melt the remaining stick of butter in a saucepan.

Add flour and cook for about five minutes, or until it looks light brown.

Slowly add the milk, whisking all the time to ensure no lumps form.

Add the nutmeg, white and cayenne pepper, salt, onion powder, Worcestershire sauce and Dijon mustard. Mix.

Add the cheese, a little at a time and mix with a spoon (not whisk). Then add the Parmesan. Mix well.

In the casserole dish, pour the macaroni.

Pour the cheese sauce in and mix together.

Sprinkle the crumbled bacon on top.

Bake for 25 minutes.

Let cool for about 10 minutes and serve.