Bring a pot of water to a boil over high heat. Add the pasta and 2 teaspoons of salt. Cook until the pasta is al dente, about 8 minutes. Drain and set aside.
Prepare the roux: Whisk together the flour and butter in a large saucepan over medium heat. It will form a paste. Slowly pour in and whisk the milk to incorporate and keep whisking until smooth and becomes thick, for about 3 to 4 minutes.
Turn the heat to low and begin adding in and mixing the handfuls of cheese into the roux. Stir in the remaining 1/2 teaspoon of salt, dijon mustard, Worcestershire sauce and the smoked paprika. Stir until all the cheese has melted and the sauce is creamy. Taste and adjust the seasonings as desired.
Add the cooked pasta into the cheese sauce and stir together until all of the pasta is nicely coated. Let cook in the saucepan for about 2 to 3 minutes. Stir together one last time, season with salt and pepper if desired and then serve and enjoy!