Cook spaghetti in salted water until al dente. Reserve ½ cup pasta water, then drain.
Season the chicken strips with Italian seasoning, paprika, garlic powder, salt, and pepper.
Heat olive oil with 2 tbsp of the butter in a large skillet over medium-high heat and sear until golden with deep seared edges and cooked through, about 6 to 7 minutes. Remove and set aside.
In the same skillet, melt the remaining 4 tbsp butter and add the minced garlic. Cook until fragrant, about 1 minute.
Pour in the heavy cream and bring to a gentle simmer.
Stir in the cream cheese until smooth and melted.
Add the Parmesan and mozzarella, stirring until the sauce is thick, creamy, and glossy. Loosen with the reserved pasta water as needed.
Add the spaghetti and toss until every strand is heavily coated in the creamy mozzarella Parmesan sauce.
Pile the spaghetti on one side and the garlic butter chicken strips on the other.
Garnish with fresh parsley, the finishing Parmesan, and cracked black pepper.
Serve hot.
