To flatten each chicken breast, place between 2 sheets of plastic wrap or waxed paper. Working from center, pound chicken with flat side of meat mallet or rolling pin until about 1/2 inch thick; remove wrap. Sprinkle chicken with basil, salt and ground red pepper.
In 10-inch nonstick skillet, melt butter over medium-high heat. Add chicken; cook 5 minutes. Turn chicken; add onion. Cook 4 to 6 minutes longer or until juice of chicken is no longer pink when center of thickest part is cut (170°F).
In small bowl, mix broth, reserved 2 tablespoons mandarin orange liquid and the cornstarch until smooth. Add to chicken in skillet; cook and stir until bubbly and thickened. Gently stir in orange segments; cook until thoroughly heated.