Season steak tips generously with Cajun seasoning. Heat olive oil and 1 tbsp butter in a heavy skillet over medium-high heat. Sear steak tips until browned on all sides, about 6-8 minutes total. Remove and set aside.

In a large pot, bring salted water to a boil and cook rigatoni until al dente according to package directions. Before draining, reserve 1/2 cup pasta water. Drain pasta and set aside.

In the same skillet used for steak, add remaining 1 tbsp butter over medium heat. Add minced garlic and sauté until fragrant, about 1 minute.

Pour in heavy cream and bring to a gentle simmer, stirring occasionally.

Gradually stir in freshly grated Parmesan cheese until completely melted and smooth. If using, add mozzarella or Fontina cheese. Season with salt, pepper, and additional Cajun seasoning to taste.

Add cooked rigatoni to the sauce, tossing to coat. Add reserved pasta water as needed, a tablespoon at a time, to achieve desired consistency.

Gently fold in seared steak tips just before serving to keep them tender and juicy.

Serve immediately, garnished with extra Parmesan cheese and freshly cracked black pepper.