Place raw elbow macaroni in colander and quickly rinse under water. Let drain.
2. In medium sauce pan (about 3.5 qt), add milk, raw elbow macaroni, salt, butter, mustard powder and nutmeg.
3. On medium heat, slowly bring milk/macaroni mixture to a simmer, stirring the macaroni frequently as it comes up to a simmer. This will separate macaroni and keep them from sticking together. DO NOT LEAVE THE STOVE! The milk mixture will come to a boil very quickly and leaving it unattended will leave a big mess on your stove stop.
4. Once mixture comes to a simmer, immediately turn down heat to LOW. Macaroni will slowly cook in the milk. Having your heat too high will evaporate the milk too quickly!
5. Continue to stir the mixture frequently so that macaroni will cook evenly and absorb milk evenly. If you don't stir your mixture frequently, you will get a big clump of macaroni in the end! Stir, stir stir!
6. Cook for about 15-20 minutes or until milk has been fully absorbed.
**If macaroni is not cooked fully, add a little more milk or water to mixture ( in small amounts) until macaroni is fully cooked. This will take about another 5 minutes.
7. When milk has evaporated, stir in grated cheese of your choice. Stir the cheese evenly into the macaroni.
8. Turn off heat. Place lid on top of pan and cover for about 5 minutes. This rest period will allow macaroni to plump up and absorb any excess milk.
9. Take a final taste and add additional salt to taste. Before serving, stir one final time to mix everything together.