Mac-N-Cheese perfection

For years I have been trying to perfect my homemade macaroni and cheese.  Often it was much easier to just stick with the old standby:  Kraft.  But since I am trying to stay away from more processed foods, I really wanted to work on homemade mac and cheese with sharp cheddar cheese sauce.   About a month ago I followed Alton Brown's recipe and that was pretty good; it seemed a little dry, but I liked the mix of ingredients.  Tonight I followed my instincts and came up with something like this:

I boiled about half a box of rigatoni pasta (it captures the sauce really well).  While that was working I melted 2 tbsp of butter in a sauce pan and added 2 tbsp of flour.  I cooked that for a few minutes and then added a full tbsp of dijon mustard (if using yellow mustard maybe use 1/2 a tbsp).  After whisking that around I poured in probably 2.5 cups of 2% milk.  (I say probably because I am honestly not sure.  I know it was at least 2 cups.  I added some crushed red pepper (just a sprinkle) and some cracked black pepper.  I let it barely barely come to a boil--as soon as I saw movement I took it off the heat--and added 1 cup of grated sharp cheddar cheese and about 1/4 cup of swiss cheese.  I whisked it in and then added about 1 tsp salt (to taste).  This sat until the pasta was ready.  I drained the pasta, mixed the two together and then in a separate bowl beat 1 egg.  I mixed a little of the cheese sauce in with the egg and then poured it back in with the pasta and cheese mix. 

I poured all of this into a greased 9" cast iron skillet.  I topped this with a mixture of 1 tbsp oil with 1/4 cup breadcrumbs and 1/4 cup parmesan cheese (or enough crumbs and cheese to still be moist, but not wet when mixed with the oil). 

FINALLY I baked the mac and cheese for about 20 minutes at 425--until everything was brown and bubbly.  This was the best mac and cheese I've ever made!  So good in fact that I went back for seconds...