Heat a large skillet over medium-high heat. Add the lean ground beef and diced onion. Cook, stirring often, until the beef is browned and the onions are softened. Drain excess grease.
Stir in the butter, garlic powder, ranch seasoning, and beef base or au jus gravy mix until melted and well combined.
Pour in the pepperoncini juice and beef broth. Mix well and allow the cooking process to continue until the liquid reduces.
Add the diced pepperoncini peppers and stir into the ground beef mixture. Cook for another 5 minutes to blend the flavors.
Toast the hamburger buns in a hot skillet or under the broiler. Spread with mayo if desired.
Spoon the meat sauce onto the buns, top with provolone or pepperjack cheese, and serve immediately.
