Bring a large pot of salted water to a boil. Add whole wheat pasta and cook according to package instructions until al dente, about 8-10 minutes. Reserve 1/4 cup of pasta water, then drain and set aside.

In a large skillet, heat olive oil over medium-high heat. Add cubed chicken, season with salt, pepper, paprika, and Italian seasoning. Cook for 5-6 minutes until golden brown and cooked through. Remove chicken and let rest, keeping drippings in the pan.

In the same skillet, add minced garlic and sauté for about 30 seconds until fragrant. Sprinkle in flour, whisking continuously to form a roux. Gradually add chicken broth and milk, stirring frequently until sauce thickens and becomes creamy, about 2-3 minutes.

Lower heat to medium-low and stir in Greek yogurt and Parmesan cheese until fully combined and creamy. If too thick, add reserved pasta water to reach desired consistency.

Return cooked chicken and drained pasta to the skillet. Toss gently until well-coated with the sauce. Optionally, add fresh spinach and allow it to wilt slightly.

Remove from heat and garnish with chopped parsley and extra Parmesan if desired. Serve immediately.