Cook the Pasta: Bring a large pot of salted water to a boil. Add whole wheat pasta and cook until al dente, according to package instructions. Reserve 1/4 cup of the pasta water before draining.
Cook the Chicken: Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add cubed chicken breast and season with salt, pepper, paprika, and Italian seasoning. Cook for 5–6 minutes, flipping occasionally. The chicken should be golden on the outside and cooked through. Remove and set aside.
Make the Sauce Base: In the same skillet, add the remaining tablespoon of olive oil. Sauté minced garlic for 30–60 seconds, just until fragrant. Stir in whole wheat flour to make a light roux, cooking for 30 seconds to remove the raw taste.
Create the Creamy Sauce: Slowly whisk in chicken broth, followed by low-fat milk. Simmer for 2–3 minutes until the sauce thickens. Reduce the heat to low and stir in Greek yogurt and Parmesan cheese. Mix until smooth and creamy. If the sauce feels too thick, add reserved pasta water, a tablespoon at a time.
Combine and Serve: Return the cooked chicken to the skillet along with the pasta and spinach (if using). Toss everything until evenly coated. Plate, garnish with parsley, and enjoy immediately.