Mix beef, cheddar, onion, 4 Tbs. pepper jelly, garlic, Worcestershire sauce, and salt in a bowl. Form into 6 patties.
Lightly coat both sides of burgers, cut sides of buns, and the grill rack (or nonstick skillet) with cooking spray. Over medium heat, cook burgers, turning, until golden brown and cooked through, about 5 minutes per side. Toast buns on grill for 2 minutes. Place patties on buns and top with 2 Tbs. pepper jelly, lettuce, and other desired toppings (we used onion rings, pimento cheese, and pickles).
