In a large pot add the milk, butter, and macaroni noodles. Turn the burner on medium and bring the mixture to a simmer, stirring often.
Reduce the heat if the milk seems to stick to the bottom of the pan and stir often until the noodles are cooked through, about 15-18 minutes. Slow and low is your friend here. If you cook this too fast and hot, the milk will curdle.
Stir in the cheese and salt until everything is melted.
Depending on the type and sharpness of cheese you may want to add up to another cup of cheese. Taste it and see. I used a moderately sharp cheddar and liked it at about 1 and ¼ cups of cheese. If I had used something milder I think I would have used more.
Serve right away.
