Sprinkle chicken with garlic seasoning blend. In a large skillet, saute chicken and onion in oil for 5-6 minutes or until chicken is no longer pink. Add garlic; cook 1 minute longer.
Stir in the tomatoes, spinach, broth, orzo, Italian seasoning and pepper flakes if desired. Bring to a boil; reduce heat. Cover and simmer for 15-20 minutes or until orzo is tender and liquid is absorbed. Garnish with cheese if desired.