Making a cheese sauce isn't rocket science. Start with bechamel and add a cheese you like that melts well.
Bechamel is easy - a tablespoon of butter and flour to make a roux, per tbsp of milk that you want to thicken. So 4/4 to thicken 4 cups of whole milk, which is enough bechamel to make a whole lot of cheese sauce. Classical recipes say to add some onion and clove to the roux, but it's also good plain as a sauce base or even with some nutmeg. Cook the roux a little bit (blonde), add your milk and bring just about up to a boil, then incorporate your cheese and you have a sauce.
Add to par-cooked pasta, put in a casserole dish, top with something crunchy if you like, and some more cheese. Bake it covered until done, then go under the broiler for a bit to get a crust. Macaroni and cheese.