Cook penne pasta, according to the directions on the package and drain the pasta.

Heat oil in a large nonstick skillet set over medium heat. Add garlic and spinach and sauté for 2-3 minutes, or until the spinach is wilted, stirring occasionally. Transfer spinach to a medium sized bowl.

Spray the skillet with cooking spray. Add chicken and sprinkle with salt. Cook chicken 6-7 minutes, or until fully cooked, mixing occasionally. Transfer chicken to the bowl with the spinach, and set aside.

Melt butter in the skillet and mix flour in with the melted butter.

Add milk and cook, whisking constantly, 3-4 minutes or until the milk thickens.

Add cream cheese and 1/4 cup Parmesan cheese and cook, whisking constantly, 2-3 minutes, or until the cheese melts.

Add drained pasta, chicken, and spinach to the sauce and cook an additional 2-3 minutes, allowing all of the ingredients to mix well and the sauce to thicken one last time. Salt and pepper, to taste.

Sprinkle with parsley and remaining 2 tablespoons Parmesan cheese, if desired.