Recipe originally from reader Cailean, but I've added a few things and written it in my own words
Author: Jane Maynard
Ingredients
16-ounce package of pasta, small shells or elbow macaroni
2 cups milk
6 tablespoons flour
1 teaspoon salt
¼ teaspoon pepper
Two pinches nutmeg (optional)
2 cups shredded cheese (Cheddar is great on its own, but doing half gruyere-half cheddar is nice. For more mild flavor, half monterey jack-half cheddar nice, too.)
½ cup Panko bread crumbs (optional)
1 tablespoon melted butter (optional)
Instructions
Put the water for the pasta on to boil.
Shred cheese. In a good-sized microwave-safe bowl, whisk together well the milk, flour, salt, pepper and nutmeg (if using). Stir in the cheese.
When water comes to a boil, add pasta and cook according to package directions.
While pasta is cooking, cook the milk-cheese mixture in the microwave on full power 1-2 minutes at a time, whisking after each time. Keep cooking until cheese is fully melted and you have a nice, smooth sauce (probably about 5 minutes total).
Drain pasta, return to pot then add sauce and mix well.
If you want to top the mac & cheese with breadcrumbs, boil the pasta in a wide, oven-safe pot (like my Le Creuset 5½ quart). After the mac & cheese is all mixed together in the pot, sprinkle evenly with panko bread crumbs (about ½ cup or so) then drizzle with butter. Place pan in oven under high broiler and cook until breadcrumbs start to brown, a few minutes. If you don't have an oven safe pot, feel free to transfer the mac & cheese to a 9" x 13" casserole dish before adding the bread crumbs and broiling in the oven.
Notes
Serves 6-8. A good rule of thumb for pasta is 2 ounces uncooked pasta per person.
Recipe by This Week for Dinner at https://thisweekfordinner.com/microwave-homemade-mac-cheese/