Preheat a large skillet over medium-high heat and add olive oil.

Add ground beef, onion, and bell pepper to the skillet. Cook, breaking up the beef, until the beef is browned and the vegetables are softened, about 7 minutes.

Stir in Worcestershire sauce, ketchup, salt, and pepper.

In a small bowl, whisk together beef broth and cornstarch until smooth. Pour this mixture into the skillet with the beef.

Bring to a simmer and cook, stirring occasionally, until the mixture thickens, about 5 minutes.

Place a slice of provolone cheese on each bun bottom, spoon the beef mixture over the cheese, and cover with bun tops.

Serve immediately while hot.