INGREDIENTS
1 lb
ground beef
2 tbsp
butter
1 small
onion
1 small
bell pepper
8 oz
brown mushrooms
2 tbsp
ketchup
1 tbsp
worcestershire sauce
1/2 tsp
kosher salt
1/2 tsp
ground pepper
1 tbsp
cornstarch
1 cup
beef broth
8 oz
provolone cheese
6
brioche hamburger buns