Cook the pasta in salted boiling water according to package directions. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add the chicken, paprika, Italian seasoning, salt, and pepper. Cook for 5–7 minutes until the chicken is golden and fully cooked. Remove and set aside.
In the same skillet, add garlic and cook for about 30 seconds until fragrant. Sprinkle in the flour and stir constantly for 1 minute.
Slowly whisk in the chicken broth, then add the milk. Simmer for 2–3 minutes until the sauce thickens slightly.
Lower the heat and stir in the Greek yogurt and Parmesan cheese until smooth and creamy.
Add the cooked chicken, pasta, and spinach (if using). Toss until everything is well coated and the spinach wilts.
Taste and adjust seasoning as needed. Garnish with fresh parsley and serve warm.