Preheat the oven to 350˚F. On the stovetop, heat a large Dutch oven (or other oven-safe pot with a lid) on a high setting.
In the meantime, mix 1 tablespoon of dressing seasoning with ½ tablespoon of onion powder in a small bowl. Evenly rub the mixture onto the roast.
Add the olive oil to the pot. Once it is hot, sear the roast until browned, about 4 minutes on each side. Remove from the heat.
Add the beef broth and the pepperoncini peppers with brine. Sprinkle roast with remaining 1 tablespoon of dressing seasoning and ½ tablespoon of onion powder. Add butter on top of the roast.
Cover and cook for 3 hours or until the meat reaches an internal temperature of 202˚F and shreds easily with a fork.
Remove Dutch oven from the heat and allow to rest for 15 minutes. Shred the beef with a fork.
To serve, split the hoagie buns. To toast the buns, bake them cut side up on a baking sheet at 350˚F for 5 to 7 minutes.
Pile on the shredded meat and top with provolone, pepperoncini peppers and a generous scoop of giardiniera.
