Step 1: Cook the macaroni according to the package directions. Make sure to cook it to al dente, as it will continue to cook slightly in the sauce. Drain the macaroni well and set aside, reserving about 1/4 cup of the pasta water.
Step 2: In the same pot (or a separate saucepan for easier stirring), melt the butter over medium heat. Once melted, stir in the heavy cream and whole milk. Bring the mixture to a gentle simmer, stirring constantly, but do not let it boil vigorously.
Step 3: Reduce the heat to low. Add the powdered cheese packet from the boxed mac and cheese, followed by the shredded sharp cheddar, Gruyere, and softened cream cheese. Stir continuously with a whisk or rubber spatula until all the cheeses are completely melted and the sauce is smooth and creamy. If the sauce is too thick, add a tablespoon or two of the reserved pasta water until desired consistency is reached.
Step 4: Stir in the Dijon mustard, garlic powder, smoked paprika (if using), and hot sauce (if using). Mix well to combine all the flavors.
Step 5: Return the cooked and drained macaroni to the pot with the cheese sauce. Gently fold the macaroni into the sauce until every noodle is evenly coated. Taste and season with salt and freshly ground black pepper as needed.
Step 6: Serve immediately. Garnish with fresh chopped chives or parsley, if desired, for a touch of freshness and color. Enjoy your ultimate Gourmet Boxed Mac and Cheese!