PW's original recipe is here. We just don't really mess with mac n' cheese.
4 cups dried macaroni
1 whole egg, beaten
4 tbsp butter
¼ cup all-purpose flour
2½ cups whole milk
2 tsp (heaping) dry mustard
1 pound cheddar cheese, grated
½ tsp salt, more to taste
½ tsp seasoned salt, more to taste
½ tsp ground black pepper
Cook macaroni until slightly firm. Drain and set aside.
In a small bowl, beat egg.
In a large pot, melt butter and sprinkle in flour. Whisk together over medium-low heat. Cook mixture for five minutes, whisking constantly. Don’t let it burn.
Pour in milk, add mustard, and whisk until smooth. Cook for five minutes until very thick. Reduce heat to low.
Take ¼ cup of the sauce and slowly pour it into beaten egg, whisking constantly to avoid cooking eggs. Whisk together till smooth.
Pour egg mixture into sauce, whisking constantly. Stir until smooth.
Add in cheese and stir to melt.
Add salt and pepper. Taste sauce and add more salt and seasoned salt as needed! DO NOT UNDERSALT.
Pour in drained, cooked macaroni and stir to combine.
Serve immediately (very creamy) or pour into a buttered baking dish, top with extra cheese, and bake on 350° for 20-25 minutes or until bubbly and golden on top.