From "The Mac + Cheese Cookbook - Homeroom"
For the Bechamel:
- 3 cups whole milk
- 1/2 cup unsalted butter
- 1/2 cup all-purpose flour
- 2 teaspoons kosher salt
For the Mac & Cheese:
- 1/2 lb dried elbow pasta
- 2 cups Bechamel
- 1 1/2 cups grated 2-year-aged, extra-sharp Cheddar cheese
- 1/2 cup grated Pecorino Romano cheese
Make the bechamel sauce: Heat the milk in a pot over medium heat until it just starts to bubble, but is not boiling, 3 to 4 minutes. Remove from heat.
Heat the butter over medium heat in a separate, heavy-bottomed pot. When the butter has just melted, add the flour and whisk constantly until the mixture turns light brown, about 3 minutes. Remove from the heat.
Slowly pour the warm milk, about 1 cup at a time, into the butter-flour mixture, whisking constantly. It will get very thick when you first add the milk, and thinner as you slowly pour in the entire 3 cups. This is normal.
Once all the milk has been added, set the pot back over medium-high heat, and continue to whisk constantly. In the next 2 to 3 minutes the sauce should come together and become silky and thick. After conducting the spoon test, add the salt.
Make the mac & cheese: Cook the pasta in salted boiling water until a little less than al dente. Drain, rinse the pasta wiht cold water, and drain it again.
Add the sauce and both cheeses to a large, heavy-bottomed pot and cook over medium heat. Stir until the cheese is barely melted, about 3 minutes. Slowly add the cooked pasta, stir, and continue cooking while stirring continuously until the pasta is hot and steaming, another 5 minutes.