Heat olive oil in a skillet over medium heat.
Add sliced onions and bell peppers to the skillet.
Stir in the sliced mushrooms and cook until softened.
Increase the heat to medium-high and add the ground beef.
Season with salt and pepper as the beef cooks.
Cook until the beef is browned and cooked through, about 5-7 minutes.
Reduce heat to low and lay cheese slices over the beef mixture.
Prepare hoagie rolls by slicing them open without cutting all the way through.
Spoon the beef and cheese mixture into the hoagie rolls.
Serve immediately and enjoy!
