Season the chuck roast on all sides with salt, pepper, smoked paprika, garlic powder, and onion powder.
Sear the beef in olive oil over medium-high heat for 3 to 4 minutes per side until deeply browned.
Whisk together beef broth, ketchup, Worcestershire sauce, brown sugar, vinegar, and tomato paste.
Add onion and garlic around the beef in the Dutch oven, then pour the sauce over everything.
Braise covered at 300°F for 3.5 to 4 hours, or cook on LOW in a slow cooker for 8 hours.
Shred the beef with two forks, return it to the sauce, and stir to combine.
Pile onto toasted buns with your choice of toppings and serve immediately.