Bring a large pot of salted water to a boil and cook penne pasta according to package directions until al dente.
While pasta is cooking, toss the steak tips in a bowl with the Cajun seasoning until evenly coated.
Heat olive oil in a large skillet over medium-high heat. Add the steak tips in a single layer and sear for 2-3 minutes per side until browned and cooked to desired doneness. Remove steak from skillet and set aside.
In the same skillet, reduce heat to medium and melt the butter. Add minced garlic and cook for 1 minute until fragrant.
Whisk in the heavy cream and black pepper. Bring to a gentle simmer and let cook for 3-5 minutes until slightly thickened.
Whisk in the Parmesan cheese until melted and smooth.
Add the cooked penne and seared steak tips to the skillet. Toss until the pasta and meat are thoroughly coated in the sauce.
Garnish with chopped parsley and serve immediately.