Heat a heavy skillet over medium-high heat and add olive oil and butter. Season steak tips with salt, pepper, and Cajun seasoning. Sear for 4-5 minutes until browned. Remove and keep warm.

In a large pot, bring salted water to a boil. Cook rigatoni according to package instructions, about 10-12 minutes, stirring occasionally. Reserve ½ cup water, then drain and set aside.

In the same skillet, reduce heat and add butter. Once melted, add minced garlic and sauté until fragrant, about 30 seconds.

Pour in heavy cream, stirring continuously until it simmers. Add Parmesan cheese gradually, stirring until melted and creamy. If using, add mozzarella or Fontina cheese.

Season the sauce with salt, pepper, and additional Cajun seasoning to taste. Stir to combine.

Add the drained rigatoni into the skillet, tossing gently to coat. If the sauce is thick, mix in reserved pasta water to reach desired consistency.

Fold in the seared steak tips before serving to keep them juicy while soaking up some sauce.

Plate the dish while hot, garnishing with extra Parmesan, a sprinkle of pepper, and optional hot sauce. Serve immediately.