Preheat oven to 425 degrees and spray a 9x13-inch baking dish with non-stick cooking spray.
Boil 4-6 quarts of water in a large pot. Add a tablespoon of kosher salt and pour in uncooked pasta. Cook about 3 minutes less than the package directions call for. Drain and set aside.
Place the empty pot back on the stove and add butter. Melt over medium heat. Whisk in flour and cook for 2-3 minutes, stirring often, until golden. Whisk in the milk and heavy cream. Simmer, whisking frequently, until the sauce thickens; 3-5 minutes.
Whisk in the a salt, black pepper, ground mustard, garlic powder, onion powder and dijon mustard.
Turn off the heat and add the Velveeta, Parmesan and 3 1/2 cups of the sharp cheddar. Stir constantly until all of the cheese is melted. Taste and adjust seasonings as desired.
Add the drained macaroni to the pot and stir to coat, then pour the mixture into the prepared baking dish.
In a small bowl, combine the topping ingredients - crushed pretzels, 1/2 cup of shredded cheddar, Panko breadcrumbs and dried parsley. Sprinkle evenly over the macaroni.
Bake uncovered for 15-18 minutes, or until golden brown and bubbly. Let rest 10 minutes before serving.
Notes
This recipe was modified Nov. 2022. It originally called for 5 ounces of condensed cheddar cheese soup which I replaced with Velveeta.