Preheat oven to 425°. In a large pot, boil water and cook cauliflower for 8-10 minutes, drain and let cool. In a large bowl, combine sour cream, mayonnaise, 1/2 of crumbled bacon, 3 tablespoons of chives, 1 cup of cheese, mushrooms and cauliflower and mix well. Place in baking dish and cover with remaining cheese and rest of bacon crumbles. Bake for 15-20 minutes until cheese is melted. Top with remaining chives and serve! Enjoy!!