2 medium yellow onions, thinly sliced into rings
3 tablespoons butter
1 cup plus 3 tablespoons beef broth, divided
4 boneless skinless chicken breasts, pounded to even thickness
1 tablespoon oil
salt and pepper, to taste
1 teaspoon Italian blend herbs/Italian seasoning (OR ¼ teaspoon dried basil + ¼ teaspoon dried thyme + ½ teaspoon dried oregano)
2 tablespoons flour
4 slices provolone cheese
4 slices swiss cheese
¾ cup shredded parmesan cheese
fresh thyme or parsley and cracked black pepper for topping (optional)