Combine 1/4 cup barbecue sauce, seasoning and jalapeños in a small bowl. Knead spice mixture into ground beef and roll into 6 patties.
Brush grill grate with oil or coat with nonstick cooking spray. Light grill using Kingsford® briquets.
Grill burgers for 12-16 minutes on a covered grill until burgers are cooked through, turning once. In last 6-8 minutes of grilling time, place onions on grill. Top burgers with cheese during last minute of cooking time. Lightly spread butter on bun. Grill bun, buttered side down, until lightly toasted.
Serve burgers on buns and top with grilled onions, barbecue sauce and your favorite toppings.