Old-Fashioned Baked Macaroni and Cheese

Preheat the oven to 350 degrees F. Lightly butter a 9x13-inch casserole dish and set aside. Shred all blocks of cheese and mix together in a large bowl; set aside.
Bring a large pot of salted water to a boil. Cook the pasta according to package directions until just al dente. Drain and set aside.
In a small bowl, combine the garlic powder, paprika, salt, and pepper; set aside. Melt the butter in a large skillet over medium heat. Add half of the seasoning mix and stir for about 30 seconds. Whisk the flour into the butter to make a roux. Cook for 1–2 minutes, stirring frequently.
Gradually whisk in the evaporated milk, followed by the heavy cream. Keep whisking until fully combined and the sauce begins to thicken. Stir in the remaining seasoning and Dijon mustard.
Add half of the shredded cheese to the sauce, one handful at a time. Whisk well between each addition, making sure it fully melts before adding more. In a large bowl, mix the cooked pasta with the cheese sauce. Pour half of the pasta mixture into the prepared casserole dish. Sprinkle with half of the reserved shredded cheese. Add the remaining pasta mixture on top and finish with the rest of the shredded cheese.
Bake at 350 degrees F for 25-30 minutes until hot and bubbly. Switch the oven to broil and cook for an additional 2 minutes, or until the top is golden brown.