Melt Spread in large nonstick skillet over medium heat and cook onions and peppers, stirring occasionally, until onions are golden and tender, about 20 minutes. Remove and set aside.
Evenly spread 1/4 cup Hellmann's® or Best Foods® Real Mayonnaise, then jam on one side of bread slices. Evenly top 4 slices with 4 slices cheese, bacon, onion mixture, then remaining 4 slices cheese and remaining bread slices.
Evenly spread outside of sandwiches with remaining 1/4 cup Mayonnaise. Cook sandwiches in same skillet over medium heat, turning once, until golden brown and cheese is melted.