I grew up on “Susan’s Mac and Cheese” in the old Good Housekeeping book. It was made with Velveeta - I know it’s not cheddar, but something about hot Velveeta in Mac and Cheese is incredibly comfort food. My family’s always adored it.
The other distinctives are you start your white sauce for the cheese by sauteing minced onion - just a couple of teaspoons - in butter. Adds something special. You are also supposed to put a touch of mustard powder in it, but my youngest always objected.
But to me, the really great idea was instead of using crumbs, we would make our own croutons - just saute cubes of bread in butter at the end and sprinkle them all over the top of the dish before baking. For us, the whole dish is actually an excuse to eat buttered, toasted bread cubes along with gooey hot cheese -— Yum!
LOL! NOTHING melts like Velveeta, and is still cheese.
For a ‘gooey’ M&C, that sounds really good.
Try that recipe I posted, but go ahead & use some Velveeta in it; I think my mother probably did on occassion. Everyone I’ve ever served it to liked it, even though it is nothing like what they are used to calling M&C. It is moist, but fully ‘set’.