To make this French Onion Flavored Chicken gluten-free, confirm that the beef broth and cornstarch are certified gluten-free. Most plain cornstarch is naturally gluten-free, but cross-contamination can occur, so checking the label is important. Also verify that the provolone cheese contains no gluten-based additives. Serve with gluten-free sides such as mashed potatoes, rice, roasted vegetables, or gluten-free bread.