Yeah, especially for things like cheese sauces I find that it's better to just grate it yourself. It will _not_ melt correctly otherwise, and the additives mess with sauces more than you'd think.
Agreed. I went down this rabbit hole last year, going as far as even buying sodium citrate that's supposed to help it melt together, with mixed results and awful taste.
Never came close to anything resembling a well melted, good tasting sauce.
Still buy your cheese in blocks and hand grate, but sodium citrate is better made at home for sauces I think. Titrate baking soda with a tart citrus juice (e.g., lime or lemon, whatever fits with the dish) over medium heat till incremental juice doesn't induce extra bubbles. You'll have a roughly neutral pH, citrus-flavored solution of sodium citrate suitable for nacho cheese and a variety of other dishes.
I wouldn't do this in a restaurant but a quick cheese sauce for something like nachos. Just pop some shredded cheese in the microwave with some heavy cream or half and half. Adjust to taste / texture. Stir well.
Mornay, citrate, and evaporated milk approaches work but I'm lazy so I just do the cream approach for "queso".
Honestly for a quick cheese sauce for nachos I don't think you can beat Velveeta. It doesn't get easier, and I prefer the flavor of American cheese for things like that.
Pre-shredded cheese melts just fine, although I've never tried it in a straight cheese sauce (for those I just dice a block of cheese because it's easy and cheaper). But I use it in things like lasagna or other casserole type dishes, and I've never had an issue with its ability to melt properly.
Yeah it'll melt like that. If you try in things like a cheese sauce for mac and cheese...it melts poorly into the milk and messes with the consistency/thickness.
