Heat Hellmann's® Real Mayonnaise in large nonstick skillet over medium heat and cook onions covered, stirring frequently, until golden about 20 minutes. (Stir in a little water if onions start to get too dark.) Stir in mustard and syrup and cook, stirring frequently, until syrup is absorbed, about 2 minutes.
Combine ground beef, Knorr® Recipe Onion Soup Mix and water in large bowl until well blended; shape into 8 patties. Grill or broil until done. Grill peameal bacon until crisp.
Arrange peameal bacon, then burgers on buns. Top with caramelized onions.