Place cauliflower in large pot, fill with water to cover. Bring to boil over medium-high heat. Cook until tender, about 20 minutes. Drain well.
Place cauliflower in bowl of food processor and add remaining ingredients. Pulse until blended and smooth. Serve immediately with additional sour cream, Cheddar cheese, bacon, and green onions, if desired.
Test Kitchen Tip: To prepare using 1 package (12 ounces) frozen riced cauliflower, heat cauliflower according to package directions. Continue with Step 2, as directed.