Begin by slicing the ribeye steak into strips, about 1-inch thick, and season with salt and pepper. Let sit for 10 minutes.

In a large pot, bring salted water to a rolling boil. Cook rigatoni until al dente, about 10-12 minutes. Reserve ½ cup pasta water, then drain.

In a skillet, melt 2 tablespoons of unsalted butter over medium-high heat. Sear the steak strips for 2-3 minutes until browned. Remove and set aside.

In the same skillet, lower heat and add another tablespoon of butter. Stir in minced garlic, Dijon mustard, smoked paprika, and chili flakes for 1-2 minutes.

Add the cooked rigatoni and seared steak to the skillet, tossing to coat with the sauce. Stir in reserved pasta water as needed.

Transfer to serving plates and garnish with chopped parsley. Serve immediately.