Cook the 2 cups of pasta in 2 quarts of boiling salted water for one minute less than the package directions. (Cook for 20 minutes if you want soft, large pasta. See recipe notes.)
Drain the pasta, but don't rinse it. Allow the pasta to cool for at least 5 minutes. If it's too hot, the sauce won't stick.
In a large heavy bottomed skillet, heat up the water over medium heat for two minutes, then sprinkle in the sodium citrate and whisk until dissolved. Reduce the heat to medium and slowly whisk in the milk, and heat for two minutes while whisking constantly. Don't allow the milk to boil.
Turn the heat to low and gradually add the grated cheese one handful at a time, roughly ½ cup, while whisking. Whisk in the paprika, turmeric, and salt. Taste and adjust seasonings. Allow the sauce to sit for 5 to 10 minutes to thicken. Preheat the broiler.
Add the cooked and cooled pasta to the sauce a little at a time. There should be a good ratio of sauce to pasta. Stir gently with a spatula or a large wooden spoon until it's evenly coated. Taste and adjust seasonings if desired.
Divide the mac and cheese evenly between the buttered ramekins and place on a cookie sheet or use a buttered 8x8-inch baking dish. Sprinkle with the grated American then the cheddar. Broil on high for 2 minutes, or until it has browned on top. Enjoy immediately.