Cook the pasta according to package directions. Reserve ½ cup of pasta water (for thinning, if needed). Drain pasta and set aside.
In the same pasta pot, melt the butter over medium-high heat. Whisk the flour into the milk until dissolved. Add the milk-flour mixture, Dijon mustard, paprika, salt, and pepper to the pot and whisk thoroughly to incorporate.
Bring the milk mixture to a boil over medium-high heat and reduce to medium heat. Stir continuously to prevent burning. Cook until thickened, about 4 to 5 minutes.
Remove the sauce from heat. Stir in the cheeses until melted and well incorporated. Add more salt and pepper, as needed. If the cheese sauce is too thick, thin it with a little bit of the reserved pasta water, until you achieve the desired consistency. Add the pasta and stir until the pasta is well coated.
Lightly mist a frying pan with cooking spray or a drizzle of olive oil. Add the breadcrumb ingredients and toss to coat with the oil. Toast on medium heat until lightly golden, about 2-3 minutes.
Transfer the mac and cheese to a serving dish and top with toasted breadcrumbs. Serve and enjoy!