French Onion Chicken

Name: French Onion Chicken
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Cuisine: American
Ingredients: 4 boneless skinless chicken cutlets ((16 to 20 ounces total)); 2 teaspoons olive oil; 2 medium yellow onions (thinly sliced); 1 tablespoon balsamic vinegar (or more as needed); 1 tablespoon Worcestershire sauce; ½ teaspoon dried thyme or 1 teaspoon fresh thyme leaves; 3 ounces Gruyère cheese (coarsely grated (about 1 cup)); ½ cup all-purpose flour (or gluten-free flour mix*); 1 teaspoon kosher salt; pepper (to taste); ½ teaspoon paprika; 2 teaspoons unsalted butter; 1/2 cup chicken broth