In a large skillet, add your ground beef and thinly sliced onion.

Sauté over medium heat until the beef is cooked through.

Drain any grease and add the meat and onion mix to your slow cooker.

To the slow cooker, add the oatmeal, beef broth, beefy onion soup mix, Worcestershire sauce, garlic powder, and black pepper.

Stir to combine.

Cover and cook on low for 3-4 hours.

Right before serving, place the slices of provolone cheese on top and cover for 5 minutes until the cheese is melty.

Serve on brioche buns or slider buns.