1 pound lean ground beef
2 tablespoons butter
1 small yellow onion, diced
1 small green bell pepper, diced
8 ounces brown mushrooms minced
2 tablespoons ketchup
1 tablespoon Worcestershire sauce
1/2 teaspoon Kosher salt
1/2 teaspoon fresh ground black pepper
1 tablespoon cornstarch
1 cup beef broth
8 ounces Provolone Cheese Slices, chopped (use 6oz if you don’t want it very cheesy)
6 brioche hamburger buns