In a large pot, boil pasta in salted water according to package directions until tender. Drain, rinse, and set pot aside.
In a large saucepan set over medium heat, melt 3 tablespoons of butter in a large saucepan until bubbling. Add in the flour and whisk for 2 to 3 minutes, until combined and golden brown.
Slowly whisk in the milk and heavy cream, mixing until smooth. Whisk in the salt, pepper, and nutmeg.
Add the cream cheese and whisk until melted and smooth. Repeat with the grated cheeses, adding them 1 cup at a time and whisking until smooth and thick, for 4 to 5 minutes.
Remove the saucepan from the heat and pour the cheese sauce over the cooked pasta. Serve immediately.
OPTIONAL:
Transfer the mixture to a greased 13x9 casserole dish.
In a small bowl, combine the panko crumbs and melted butter, then sprinkle over the top.
Bake in a 350 degree F oven until bubbly and golden brown, for 25 to 30 minutes.
Serve immediately.
Video
Notes
How to Reheat Mac and Cheese with Cream Cheese Leftovers
Warm individual servings in the microwave or on the stove, adding a splash of milk as needed to get it creamy again. To reheat in the oven, bake, covered in foil, for 20 to 25 minutes at 350 degrees F.