Heat a large nonstick skillet over medium high heat. Add oil to pan; swirl to coat. Add flour and garlic; cook until garlic is browned (about 2 minutes), stirring constantly. Add milk and broth, stirring with a whisk; bring to a simmer, and cook 2 minutes or until thickened. Add cheese, stirring until cheese melts. Add remaining 1/2 teaspoon pepper, and spinach; stir until spinach wilts. Add pasta and chicken; toss to combine.