Keep the noodles warm after cooling by floating in water that is hot to touch.
In a wide frying pan or chafing dish over high heat on a range, melt butter until it is lightly browned.
Add 1/2 cup of the cream and boil rapidly until large shiny bubbles form; stir occasionally. (Do this ahead, then reheat.) Reduce heat to medium or place chafing dish over direct flame.
Drain noodles well and add to the sauce.
Toss vigorously with 2 forks, and pour in the cheese and the remaining cream, a little at a time€”about three additions.
Season with salt and pepper and grate nutmeg generously over the noodles (or use about 1/8 teaspoon of the ground spice).