BOIL: Boil pasta to al dente in heavily salted water according to package directions. Drain and set aside. Reserve about ½ cup of pasta water.
MAKE A BLONDE ROUX: Melt 4 tablespoons (½ stick) of butter over medium heat. Whisk in ¼ cup of flour slowly, stirring out all the lumps. Cook for about 5 minutes while stirring, allowing the roux to darken slightly to a white sand color (should not be browned!). This is a blonde roux.
MAKE A BÉCHAMEL: Whisk in the warmed milk a little at a time until it is all incorporated and mixture is smooth. Bring to a simmer, lower heat, then continue to cook while stirring frequently for about 5 minutes until thickened. Add in 2 teaspoons cajun seasoning and 1 teaspoon hot sauce. Start adding in white cheddar, gouda, gruyere, and cream cheese a little at a time while stirring. Stir until cheese is melted into the sauce and remove from heat. Add salt and pepper to taste.
MIX IT ALL TOGETHER: Fold in the cooked pasta with a splash of pasta water to the cheese sauce. Mix until combined.
MAKE THE TOPPING: In a saucepan melt 2 tablespoons of butter. Add crumbled crackers or panko breadcrumbs into the pan. Toast over medium heat until golden brown, stirring occasionally. Sprinkle the buttered crackers over the top of the mac and and cheese and serve warm!
