Start by bringing a large pot of salted water to a rolling boil. Add the whole wheat pasta and cook according to package instructions until al dente, typically around 8-10 minutes. Before draining, reserve 1/4 cup of the pasta cooking water, then drain the pasta and set aside.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the cubed chicken breast, seasoned with salt and pepper, and cook for about 5-6 minutes until golden brown. Transfer to a plate and cover to keep warm.

In the same skillet, add more olive oil if needed and toss in minced garlic. Sauté garlic for about 1-2 minutes until fragrant, being careful not to burn it.

Sprinkle the whole wheat flour into the skillet with the garlic, stirring continuously to form a roux. Cook for about 30 seconds.

Gradually whisk in chicken broth and low-fat milk until smooth. Simmer over medium heat for 2-3 minutes until thickened.

Reduce heat to low and stir in Greek yogurt and grated Parmesan cheese until melted. Add reserved pasta water if the sauce is too thick.

Bring back the sautéed chicken and drained pasta into the skillet, folding gently. If using spinach, toss it in now to wilt slightly.

Serve immediately on warm plates, garnishing with parsley and extra Parmesan cheese.