Learn the basics of sauces from a French cooking book/course.

Make a blonde roux, for 4 pounds of cheese, add 1.5 cups of milk and 2 cups of half and half. Add in the shredded cheese saving about a pound to a pound and a half for layering. Add 4 tsp of sodium citrate. Voila you have a cheese sauce that won’t break on you that pours into the pasta easily.

As a non-American, how much pasta goes with all that cheese? And how many serves do you get out of it?
Generally I use 1 pound of pasta per 2 pounds of cheese. Four pounds makes a casserole dish that is 12"×8"×4" or 12-16 servings
Ok, thanks! I tried to make mac and cheese twice, years ago, and they came out pretty good, but even though I don't remember the recipes I'm certain I went shorter on the cheese (it was 4-5 servings, not even close to a whole pound), shame on me. Next time I'm also trying with the citrate, I've been wanting to use it for some cheese sauces for quite a while but it's not something they sell at any store here and I always remember when I'm about to cook. Also, what cheese(s) do you use?

I personally use 1.5 lbs ofCuba NY Extra Sharp White Cheddar, 1 lb of mozzarella, 1 lb of Gruyere, and .5 lbs of smoked Gouda.

Swap the Gouda for a nice buttery Parmesan if you have $$$