Mac'n'cheese'n...

Preheat oven to 350F.

Cooking by explosion was successful:
5-6 strips bacon, cooked and chopped, back in the pan with:
1/3lb kielbasa, diced
1/2 onion, minced
1/2lb sliced baby bella mushrooms
Cook 'til the kielbasa is browned and/or the onions are just translucent. Take off heat and set aside.

Cook 1.5lb pasta of choice. While pasta is cooking:
In a medium saucepan, melt 3T butter over medium-low heat
Add 1c. cultured buttermilk and 1c. half-n-half or milk.
Scald.
Whisk in 3T corn starch and a healthy dash of pepper.
Slowly add 2lb shredded cheese of choice, whisking steadily.
Adjust consistency by adding milk/half-n-half until just creamy.

Drain pasta well. Pour the cheese sauce over it and stir.

In a deep 9x13 (3.5qt minimum):
Grease the pan lightly.
Make a layer of the bacon/onion/kielbasa/mushroom mix.
Pour the pasta and cheese over it. Don't stir, just give it a jiggle to settle.
Top with a good dash of parmesan-romano and a few tablespoons of bread crumbs.

Into the oven for 45min at 350F, or until bubbling and lightly browned.