Preheat the oven to 350 degrees F and put a large pot of salted water on to boil.
Add the macaroni to the boiling water and cook until al dente
, 8 to 9 minutes. Drain
Meanwhile, in a 4-quart pot, melt
2 sticks of the butter over low heat and then add the flour, mustard
powder, seasoned salt, salt and pepper. Cook 2 minutes, stirring with a whisk
. Add the milk a little at a time, whisking, and cook until thickened and smooth, 6 to 8 minutes. Remove the pot from the heat and stir in the American and gouda
cheeses along with 4 cups of the Cheddar
until melted and thoroughly combined. Add the cooked macaroni
and stir well.
Pour the macaroni mixture into a 3-quart baking dish
with the remaining 1/2 stick butter. Sprinkle the remaining 1 cup Cheddar on top, then sprinkle with the smoked paprika. Bake until the cheese is browned on top, 25 to 30 minutes. Serve hot.