Preheat oven to 350°F. Lightly spray an 8x8 baking dish with cooking spray and set aside.
In a large pot of boiling water, place cauliflower in a steamer basket and cook 7 to 9 minutes, or until just tender. The cauliflower can cook in the microwave with a little water if you do not have a steamer basket.
In a large bowl, gently mix cooked cauliflower, sour cream, 1 cup cheese, half the scallions, half the bacon, salt, and pepper. Spoon mixture into the baking dish and sprinkle with remaining cheese and bacon.
Bake 18 minutes, or until heated through. Sprinkle with remaining remaining scallions and serve.