Step 1

Preheat oven to 400 degrees. Heat oven-safe skillet over medium-high heat.  Add butter to skillet and let melt. Add sliced onions and stir around to coat with butter. Continue to cook, stirring often, for about 15 minutes or until onions are translucent and softened.

Step 2

Meanwhile, sprinkle chicken breasts with olive oil, salt, pepper, and thyme. Once onions are done cooking, remove onions from the skillet and set aside.  Place chicken breasts in pan and cook for 5 minutes per side.

Step 3

Remove chicken from skillet and place on a plate. Cover with a paper towel to keep warm.  Return onions to skillet and sprinkle the cornstarch or flour over onions. Stir. Pour in beef broth and use a whisk to stir the mixture and make sure the cornstarch is completely dissolved.

Step 4

Once it is thickened, add the chicken back into skillet and spoon sauce all over the chicken. Top one slice of provolone cheese and one slice of Swiss cheese over each chicken breast. Transfer oven-safe skillet to preheated oven and cook for 8-10 minutes, or until the cheese is melted and chicken is cooked through.

Step 5

Spoon sauce and onions over the chicken. Garnish with parsley or Italian herbs.