Cut steak into even cubes and season with Cajun seasoning, salt, and pepper. Heat skillet over medium-high, add olive oil and butter, then sear steak for 4-5 minutes until browned.

In a large pot, boil salted water, then add rigatoni and cook until al dente, about 8-10 minutes. Reserve ½ cup pasta water, drain rigatoni.

In the same skillet, lower heat to medium, add remaining butter, and sauté minced garlic for about 1 minute until fragrant.

Add heavy cream, stirring constantly, and bring to a gentle simmer for 3-4 minutes. Gradually whisk in Parmesan until smooth. Add optional cheese if desired.

Fold rigatoni into sauce, adding reserved pasta water if necessary to reach desired consistency.

Fold in seared steak tips gently, ensuring they are mixed well with sauce.

Plate the dish, sprinkle with extra Parmesan and black pepper, and serve immediately.