re: Making real Mac and cheese for the first time for Thanksgiving. Give me your recipe

My recipe is pretty similar to tigernurse’s linked one, but buttermilk vs heavy cream + milk, and some of the amounts vary.

16 oz. macaroni
5 cups milk (I most often use all buttermilk, but have used 3 buttermilk and two heavy cream. You could use all whole milk, or even 2%)
1 stick butter
1/2 cup all purpose flour
1 Tbs. dried mustard
2 lbs of cheese, shredded (All cheddar, or a combo of extra sharp & mild, or extra sharp and Gruyere or extra sharp and manchego, or what you like best. Velveeta? I'll avert my eyes.)
Salt & pepper to taste (I like cayenne.)
Bread crumbs (panko is good)
Some Parmigiana Reggiano cheese, grated
A few more pats of butter

Preheat oven to 350. Butter 9 x 11 baking dish.

Cook macaroni as directed on package, but slightly undercooked. You'll be cooking it further when you bake the mac and cheese.

Melt butter in saucepan. Add flour, whisking until well combined, cooking for 2 minutes. Add milk slowly (some people heat the milk before adding it; I don't), whisking it in until smooth, do not boil. Add dried mustard & S&P. Slowly add most of the cheese, bit by bit, whisking smooth and cooking until thickened.

Combine the cheese sauce and the macaroni and pour it into the buttered baking dish.

Top with remaining cheese and the grated Parmigiana Reggiano, and then top that with a light layer of panko that has been combined with melted butter.

Bake until cheese is golden and bubbly, 30 to 45 minutes, depending on your oven. Remove from oven and let sit for 5 minutes before serving.