Spray 5-quart slow cooker with cooking spray.
Mix together spice mixture.
Trim some of the excess fat from beef but leave some on for flavor and moisture.
Rub the chuck roast down with Hellmann’s Real Mayonnaise and then sprinkle with spice mixture.
Heat a 12-inch skillet over medium-high heat and sear the beef roast on each side until browned, about 2-3 minutes.
Transfer roast to slow cooker.
In large bowl, mix melted butter, Hellmann’s Real Ketchup and Hellmann’s Burger Sauce, and brown sugar together. Then stir in onion and garlic.
Pour sauce over beef in the slow cooker.
Cover and cook on Low heat for 8 to 10 hours or until beef is tender and shreddable.
After cook time is over, remove beef and let stand 5 to 10 minutes, then shred.
Serve beef on toasted buns, and top with lettuce, and your favorite burger toppings- Hellmann’s Ketchup, Hellmann’s Real Mayonnaise, Hellmann’s Burger Sauce, Hellmann’s Spicy Dipping Sauce.