Heat a large, heavy skillet over medium-high heat. Add olive oil and butter, allowing them to melt together.

Season steak tips with Cajun seasoning, salt, and pepper. Add to the skillet and sear for 2-3 minutes on each side until browned.

In a large pot, bring salted water to a boil. Add rigatoni and cook until al dente, about 10-12 minutes. Reserve ½ cup pasta water before draining.

Return the skillet to medium heat, add another tablespoon of butter, then add minced garlic and sauté until fragrant. Pour in heavy cream and bring to a simmer.

Stir in Parmesan cheese until melted and the sauce is creamy and smooth. Adjust seasoning with salt, pepper, and Cajun seasoning.

Toss rigatoni into the cheese sauce, adding reserved pasta water if needed to achieve desired consistency.

Gently fold in the rested steak tips, mixing thoroughly. Warm everything through for 1-2 minutes.

Serve immediately, garnishing with additional Parmesan and black pepper.