Preheat oven to 375 degrees. Spray 2-quart shallow baking dish with nonstick cooking spray; set aside.
Cover potatoes with water in 4-quart saucepot; bring to a boil over high heat. Reduce heat to low and cook 10 minutes or until potatoes are tender; drain and mash.
Stir in 1 cup cheese, Hellmann's® or Best Foods® Real Mayonnaise, sour cream, green onions and 4 strips crumbled bacon. Turn into prepared baking dish and bake 30 minutes or until bubbling.
Top with remaining 1/2 cup cheese and bacon. Bake an additional 5 minutes or until cheese is melted. Garnish, if desired, with additional chopped green onions.