, Gouda, and Parmesan — as opposed to something soft like Brie, but you can do your own experiments if you're determined. I used about a cup. Then, bring a cup of water to a simmer in a medium-sized pot. Whisk in a teaspoon of sodium citrate until it's dissolved, and then whisk in all the cheese, gradually, until it's melted and gotten to the cheese consistency you're hoping for. Taste and season it with salt and pepper to your liking.
This will make a thin, more pourable cheese sauce, but for a thicker sauce, reduce the amount of water that you're simmering and proceed accordingly. You can adjust the quantity of cheese, water, and sodium citrate to the amount of cheese sauce you want. If you have a lot of cheese, you can use an immersion blender to incorporate it,Serious Eats recipe for modern macaroni and cheese.