Combine bread crumbs, mustard, seafood seasoning, pepper, and green onion in a medium bowl. Add egg, mayonnaise, and Worcestershire sauce; mix well. Fold in crabmeat. Using moistened hands, shape into 1-1/2-inch patties. Place 1 tablespoon butter and 1 tablespoon oil in a large skillet; heat over medium heat. Add half the patties and cook for 8 minutes or until golden, turning once.
Transfer crab cakes to an ovenproof serving platter or cookie sheet. Keep warm in a 300 degree F oven while cooking remaining patties. Repeat with remaining patties, butter, and oil. Serve warm. Makes about 30 crab cakes.