Preheat the smoker. Set your smoker to 250°F using oak, hickory, pecan, or cherry wood.
Season the chuck roast. Pat the chuck roast dry. Coat lightly with mustard or olive oil, then season with BBQ rub and salt if needed.
Smoke the chuck roast. Place the chuck roast on the smoker and cook until the bark is set and the internal temperature reaches about 165°F to 175°F.
Cube the beef. Remove the chuck roast and cut it into bite-size burnt-end-style cubes.
Sauce the burnt ends. Place the cubed chuck roast in a foil pan with beef broth, BBQ sauce, butter, and optional brown sugar. Toss to coat.
Finish the burnt ends. Return the pan to the smoker and cook uncovered or loosely covered until the beef reaches about 200°F to 205°F and is probe tender.
Rest the beef. Let the burnt ends rest for about 20 minutes while you make the gravy and fries.
Make the gravy. Melt butter in a saucepan over medium heat. Add diced onion and cook until softened. Add garlic and cook for 30 seconds.
Build the roux. Stir in flour and cook for 1 to 2 minutes, stirring constantly.
Add broth and flavor. Slowly whisk in beef broth. Add Worcestershire sauce, BBQ sauce, optional bourbon, BBQ rub, black pepper, and salt to taste.
Simmer the gravy. Cook until the gravy thickens enough to coat the back of a spoon. Keep warm.
Cook the fries. Cook fries until golden and crispy using an oven, air fryer, deep fryer, or griddle. Season while hot with salt, pepper, and optional BBQ rub.
Warm the cheese curds. Let the cheese curds sit at room temperature for 20 to 30 minutes before assembly so they soften better.
Build the tray. Add hot crispy fries to a large tray or cast iron skillet. Scatter cheese curds over the fries.
Add beef and gravy. Top with smoked chuck roast burnt ends, then spoon hot bourbon BBQ gravy over the tray.
Finish the toppings. Drizzle with BBQ sauce, then add pickled jalapeños, green onions, and crispy fried onions.
Serve immediately. Serve hot while the fries are crispy, the cheese is soft, and the gravy is warm.