Bring a large pot of salted water to a boil and cook penne according to package directions until al dente, 10 to 12 minutes. Before draining, reserve 1 cup of pasta cooking water. Drain pasta and set aside.

Pat steak tips dry with paper towels. Mix Cajun seasoning, garlic powder, smoked paprika, salt, and pepper in a small bowl. Rub spice mixture all over steak tips until evenly coated.

Heat olive oil in a large skillet over medium-high heat. Add steak tips in a single layer and sear for 3 to 4 minutes per side until browned on the outside but still pink in the center. Transfer to a plate and set aside.

In the same skillet, reduce heat to medium and add butter. Once melted, add minced garlic and cook for about 30 seconds until fragrant. Pour in heavy cream and milk, stirring to combine.

Add cream cheese in small pieces and whisk constantly until completely melted and smooth. Reduce heat to medium-low.

Gradually stir in grated Parmesan and shredded mozzarella, stirring constantly as cheese melts. Add 1 teaspoon Cajun seasoning and stir well. If sauce is too thick, add reserved pasta water a few tablespoons at a time until desired consistency is reached.

Add drained penne to the skillet and toss until well coated with sauce. Return steak tips to the pan along with any accumulated juices. Gently mix everything together and let steak warm through for 1 to 2 minutes.

Transfer to plates or a serving dish and garnish with freshly chopped parsley. Serve immediately.