Boil spaghetti in salted water until al dente (per package instructions). Drain and set aside.
Heat olive oil in a skillet over medium heat. Add diced onion and sauté until translucent (3–4 mins). Stir in minced garlic and cook for 30 seconds until fragrant.
Whisk in cream of mushroom soup, chicken broth, Italian seasoning, paprika, salt, and pepper. Simmer for 3–4 minutes.
Reduce heat to low. Stir in sour cream, cheddar, and Parmesan until melted and smooth.
Add cooked chicken and drained spaghetti to the sauce. Toss gently to coat evenly. Cook for 2–3 minutes to heat through.
Garnish with fresh parsley and extra Parmesan if desired. Serve warm.
