Preheat the oven to 350 degrees F.
In a large cast iron skillet, brown ground beef until a brown crust appears before breaking down the beef.
Stir until completely browned.
Move the beef to a bowl and add the butter, onions and mushrooms.
Let brown for about 2 min. before stirring, then let brown for another 1-2 minutes before stirring again.
Add the beef back into the pan.
Add the ketchup, Worcestershire sauce, salt, black pepper, and beef broth into the pan.
Scoop the mixture into the bell pepper halves and top with half the cheese.
Bake for 45 minutes in a covered pan.
Uncover, top with remaining cheese and put back in the oven for 5 minutes to melt the cheese.
Enjoy!!