Cook the pasta in plenty of salted boiling water until 2 minutes shy of the package instructions. Drain and set aside. Don’t rinse your pasta, or add oil to it.
Meanwhile, mix together the meatball ingredients until well combined, but don’t overwork the meat.
Form small 1″ meatballs and place on an oiled baking sheet. You should get around 30. Set your oven rack on the second from top level and broil the meatballs for about 5-6 minutes, until browned and done through. Give the pan a shake a couple of times so they brown on all sides. Watch carefully because they will cook fast. Their internal temperature should be 160°F. Set aside.
Preheat oven to 325°F.
In a medium saucepan, melt the butter and whisk in the flour. Cook, whisking constantly, for a minute or so. Don’t let it brown.
Slowly add the milk, while whisking to blend well. Heat, stirring constantly, until the mixture comes to a simmer and thickens slightly. Don’t let it boil.
Remove from the heat and slowly stir in the shredded cheese. Stir to encourage all the cheese to melt. Season with salt, if necessary, pepper, and a sprinkle of nutmeg.
Add the pasta to the cheese sauce and mix well. Turn into your skillet or baking dish. Nestle the meatballs into the mac and cheese.
Bake for about 20 minutes, or until bubbling throughout. You can run it under the broiler briefly if you want more browning, but watch very carefully so it doesn’t burn.