Bring a large pot of salted water to a boil and cook penne according to package directions until al dente. Drain and set aside.
Toss steak tips with Cajun seasoning in a medium bowl until evenly coated.
Heat olive oil in a large skillet over medium-high heat. Add steak tips in a single layer and sear for 4 minutes until browned. Remove from skillet and set aside.
Reduce heat to medium. In the same skillet, melt butter and sauté minced garlic for 1 minute until fragrant.
Whisk in heavy cream, scraping the bottom of the pan to release browned bits. Simmer for 5 minutes until slightly thickened.
Gradually whisk in Parmesan and cheddar cheeses until melted and smooth. Season with salt and pepper.
Add the cooked penne and steak tips back into the skillet. Toss to coat thoroughly in the sauce.
Garnish with fresh parsley and serve immediately.