01 -
Get your oven hot at 375 degrees F.
02 -
Cut your bread half lengthwise and dig out some of the middle, leaving a 1-inch edge. Smear mayo on both halves and put them on a baking sheet.
03 -
Heat the olive oil in a big non-stick pan over medium-high heat. Throw in your chopped onion, bell pepper, and mushrooms. Cook them until soft, about 2 minutes.
04 -
Toss the ground beef into the pan and break it up into tiny bits while cooking. Keep going until you don't see any pink, around 3 minutes. Pour off any extra fat.
05 -
Mix in Worcestershire sauce, salt, and black pepper. In a small bowl, stir cornstarch and beef broth together, then pour into the beef mix. Let it bubble gently for 2-3 minutes, stirring now and then, until it gets a bit thicker.
06 -
Scoop the meat mixture onto both bread pieces, spreading it out evenly.
07 -
Cover everything with your grated cheese.
08 -
Cook for about 15 minutes until the cheese melts and turns golden-brown. You can also pop it under the broiler briefly if you want it more brown.
09 -
Slice into 2-inch chunks for snacks or bigger pieces for a meal. Add some red pepper flakes for extra kick and color if you want. Dig in!.