Preheat the oven to 350 degrees and grease a 9 x 13 inch casserole dish.
Bring a large pot of salted water to a boil. Boil the pasta according to package directions, then drain and return to the pot. If the sauce is not quite done, toss the pasta with a little olive oil to keep it from sticking.
1 lb cavatappi or short pasta shape of your choice
Meanwhile, make the cheese sauce. In a large sauce pan, melt the butter over medium heat. Add the flour and whisk constantly, cooking for 1-2 minutes, until smooth and thick.
⅓ cup unsalted butter, ⅓ cup flour
Slowly drizzle in the milk and half and half, about a ½ cup at a time, whisking constantly. The mixture will be thick and gloppy at first, but will eventually thin and smooth out. Bring the mixture to a gentle simmer. Cook 3-4 minutes, stirring continuously, making sure to scrape the bottom and sides of the pan well. When the mixture is thickened enough to coat the back of a spoon, turn the heat all the way down to low.
2 ¾ cup milk, 1 cup half and half
Whisk in the salt, mustard powder, garlic, paprika, pepper, and cayenne.
1 teaspoon Kosher salt, 1 teaspoon ground mustard, 1 teaspoon garlic powder, 1/2 teaspoon black pepper, 1/4 teaspoon cayenne pepper, 1 teaspoon paprika
Stir in all of the blue cheese, 1 cup of the cheddar, fontina, and American cheese. Continue stirring until all the cheese is melted. Remove from heat.
2 cups shredded sharp cheddar cheese, ¾ cup shredded fontina cheese, ¾ cup crumbled blue cheese, ¾ cup shredded white American cheese
Pour the noodles into the greased pan, followed by the cheese sauce. Stir well.