Place the butter, ground beef, onions and peppers in a skillet over medium high heat on the stove. Saute until the beef is browned and vegetables have softened.

Drain the excess grease. Reduce the heat to medium.

Whisk together the broth and cornstarch in a bowl, and pour into the meat mixture.

Add in the worcestershire sauce, ketchup and salt and pepper to taste. Mix to combine.

Simmer until the sauce thickens and liquid is reduced.

Stir in the provolone cheese until melted. Serve the meat mixture on the buns.

Enjoy!