Bring a large pot of salted (about a palmful or 2 tablespoons) water to boil.
Preheat your oven to 325° and lightly spray a 9x9 or 8x8 casserole dish with olive oil spray.
Once the water is boiling, stir in pasta and cook 1 to 2 mintues shy of whats suggested on the package and drain.
Meanwhile, melt the butter in a 10-inch nonstick skillet. Once melted, whisk in the flour and cook for 1 minute.
While whisking, slowly pour in the half and half. Heat on medium to medium-low until the sauce thickens, whisking often. It should be the consistency of a creamy soup.
In a meidum bowl, combine both of the cheeses.
When the sauce has thickened, add 1/3 of the cheeses, dry mustard, paprika and season with salt and pepper. Stir until the cheese has melted and the sauce is smooth.
To that, add in the drained pasta and use a spatula to combine.
Place half of the macaroni and cheese sauce into the prepared pan. Sprinkle half of the remaining cheese over top. Then add the rest of the pasta and cheese sauce and the last of the cheese sprinkled over top.
Bake on the middle rack of your preheated oven for 10 minutes. Then turn on the boiler, and carefully move the pan to the highest postition in your oven. Broil until the top is golden in spots.
Remove and let cool slightly before serving.
For an extra cheesey mac and cheese, add an extra half cup grated cheddar jack!