Preheat oven to 350°. Put cauliflower in large pot, add water to cover and bring to boil. Cook, covered, until florets are tender, about 15 minutes; drain.
Add cauliflower, Hellmann's® or Best Foods® Real Mayonnaise, sour cream and salt to food processor and process until smooth. Scrape into bowl and stir in 1/2 of the cheese, the green onions and bacon.
Spoon into shallow 2-qt. baking dish and bake 35 minutes or until lightly golden and bubbly around the edges. Sprinkle with remaining cheese.