Preheat oven to 400.
Bring a large pot of salted water to a boil. Cook until almost done. Drain.
Melt butter in a saucepan. Whisk in the flour. Cook for 2 minutes on medium-low heat whisking constantly.
Slowly pour in 2 cups of milk. Continue to stir for another 2 minutes.
Add 1/2 of your cheese. Stirring until combined and melted.
Remove from heat. Add salt and paprika.
Spray baking dish, add noodles, and mix in the cheese sauce very well.
Top with remaining 2 cups of cheeses.
Bake for 15-20 minutes until golden brown. Enjoy!