Step 1: Bring 6 cups of water to a rolling boil in a medium saucepan. Add a generous pinch of salt to the water.
Step 2: Add the boxed macaroni pasta to the boiling water. Cook according to package directions, typically 7-8 minutes, or until al dente.
Step 3: While the pasta cooks, grate your cheeses. Aim for about 1 cup of a good melting cheese (like Gruyère or smoked gouda) and 1 cup of sharp cheddar.
Step 4: Once the pasta is cooked, drain it thoroughly in a colander. Do NOT rinse the pasta. Return the hot, drained pasta to the empty saucepan.
Step 5: Immediately add 4 tablespoons of unsalted butter to the hot pasta in the saucepan. Stir until the butter is completely melted and coats the pasta.
Step 6: Pour in 1 cup of whole milk (or half-and-half for extra creaminess). Add the cheese powder packet from the box, along with 1 teaspoon of Dijon mustard, 1/2 teaspoon of garlic powder, 1/2 teaspoon of onion powder, and a dash of Worcestershire sauce (about 1/4 teaspoon).
Step 7: Stir everything vigorously over low heat until the cheese powder and spices are fully incorporated into the liquid, forming a thin, slightly cheesy base.
Step 8: Gradually add your freshly grated cheeses to the saucepan, a handful at a time, stirring constantly. Continue stirring until each addition is completely melted and smooth before adding more.
Step 9: Taste the mac and cheese. Add salt and freshly ground black pepper to taste. You might find you need more salt depending on the cheeses used and how much you salted the pasta water.
Step 10: If the sauce is too thick, add another splash of milk until it reaches your desired consistency. If it’s too thin, continue stirring gently over very low heat for another minute or two, allowing it to thicken slightly, but be careful not to overcook the cheese.
Step 11: Serve immediately! Garnish with fresh chives, parsley, or a sprinkle of paprika if desired.