Bring a large pot of salted water to a boil and cook the spaghetti until al dente. Reserve 1/2 cup of pasta water before draining.

In a large skillet, heat olive oil and butter over medium-high heat. Season chicken with garlic powder, paprika, salt, and pepper. Sear for 3-4 minutes on each side until golden brown and cooked through, then remove and set aside.

In the same skillet, sauté minced garlic for 30 seconds. Pour in chicken broth and heavy cream, mixing to combine. Add cream cheese and whisk until smooth. Stir in cheddar and Parmesan until melted, then mix in Italian seasoning and red pepper flakes.

Toss the cooked spaghetti into the sauce until well coated. Add chicken back to the pan and stir to combine. If the sauce seems too thick, use a splash of reserved pasta water to adjust the consistency.

Plate the creamy chicken spaghetti, garnish with extra Parmesan and fresh parsley or basil, and drizzle with melted butter before serving.