Cook macaroni in large pot of salted water until al dente. Drain, then stir in a pat of butter to prevent sticking.
Preheat oven to 400º
In large skillet on medium heat melt 4 tablespoons of butter, stir in flour and dry mustard to make a roux. Cook for about 2 minutes.
Gradually add the milk, whisking continuously until the mixture is smooth.
Slowly bring to a boil, whisking continuously, until sauce thickens.
Season with ½ teaspoon paprika and salt to taste.
Mix all the cheeses together, then stir half of the cheese into sauce.
Mix well until cheese has melted and sauce is smooth.
Add macaroni and combine well.
Pour mixture into baking dish.
Combine remaining cheese, breadcrumbs and ½ teaspoon paprika together.
Sprinkle over macaroni mixture.
Bake for 15-20 minutes until top is golden brown.