I'm posting this partly because my only copy is on a tiny scrap of paper, which is getting old....
2 oz. butter (1/2 stick)
1/4 cup all-purpose flour
2-3/4 cup milk (regular, skim, whatever)
1 tsp salt (or to taste)
1/8 tsp pepper (or to taste)
1/8 tsp nutmeg (or to taste)
1/8 tsp cayenne or red pepper (optional)
1 lb pasta shells, penne, or similar
14-18 oz. shredded cheeses: fontina, cheddar, gruyère, aged gouda, etc.
1/2 cup or so of breadcrumbs
Any other mix-ins, like chopped ham, etc.
1. Set the (salted) water to boil for the pasta, and grate the cheese. (How much cheese? When the amount seems embarrassing, you have enough. I've never measured my cheese, I just keep shredding whatever I've got until it looks like a ridiculous amount, definitely more than 3/4 lb. The quality of your cheese determines the quality of your dish. Use more than one kind, and don't be afraid to experiment.)
2. Heat the milk to just below boiling. I do this in the microwave, right in my glass measuring cup. You can do it in a pot on the stove.
3. Melt the butter over low heat in a large nonstick pot (I use a big saucier, a deep pot with rounded sides, great for stirring). When it starts to bubble, gradually stir in the flour, and whisk, cooking for one minute. It will turn pale gold. (A rubber whisk is the ideal tool for this recipe. And you've just made a French roux, more or less.)
4. Slowly whisk your hot milk into the roux until it bubbles and thickens. This can take awhile. (Now you're making Béchamel.) Keep stirring; I sometimes raise the heat a bit to help this along. Don't forget to cook the pasta when the water boils.
5. When your Béchamel is thickened and somewhat bubbly, take the pot off the heat and add the spices and the cheese, stirring until they are all melted and smooth. (This is sauce Mornay, or close enough. At this point, you can also stir in chopped ham, prosciutto, sautéed mushrooms, tiny pieces of roasted tomatoes, or whatever you want to add to the dish. Or you can put that stuff on top, later, if you prefer.)
6. Stir the cooked, drained pasta into the sauce and put it back on the burner to heat for about a minute. Taste to see if it needs more salt or spice. Pour into a large, shallow baking dish (or a series of smaller ones if you want to freeze some).
7. Top liberally with breadcrumbs. I like panko. You can mix yours with a couple of teaspoons of melted butter if you like. (I don't bother; I'm already staggered by the amount of fat and cholesterol in this dish. Omitting the butter makes me feel noble.) Put it under the broiler for a few minutes, until the top is golden and crispy. Serves 6 to 8.