Heat olive oil in a large skillet over medium heat.
Add sliced onion and bell pepper to the skillet.,
Add ground beef to the skillet, breaking it apart with a spatula.
Season the mixture with garlic powder, salt, and pepper.
Cook the beef until fully browned, about 6–8 minutes.
Place the provolone cheese slices over the beef mixture.
While the cheese melts, warm the hoagie rolls in the oven or toaster.
Once the cheese has melted, stir to combine it with the beef mixture.
Spoon the beef and cheese mixture into the hoagie rolls.
