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 1/4 teaspoon dried basil + 1/4 teaspoon dried thyme + 1/2 teaspoon dried oregano)
2 tablespoons flour
4 slices provolone cheese
4 slices swiss cheese
3/4 cup parmesan cheese
fresh thyme or parsley and cracked black pepper for topping (optional)