Remove the stem of the cauliflower and discard. Then break, or cut, the cauliflower into chunks. Set it aside for a minute or so.
Pour the chicken broth or stock into a 5 1/2 quart pot and bring to a boil. Reduce to a simmer and then add in the cauliflower. Cover and steam until tender but not soft. This step takes about 10 minutes.
Drain the cauliflower and place it into a bowl. Using a potato masher, mash the cauliflower until you get the desired consistency. If you prefer a smooth mash then either use a hand mixer or food processor to process until smooth.
Preheat the oven to 350 degrees.
Mix the butter, sour cream, grated parmesan cheese, shredded cheese, cooked bacon crumbles, salt, and pepper into the cauliflower mash. Give it another taste for salt.
Spread the cauliflower mash into an 8 x 8 casserole dish, sprayed with cooking spray.
Bake for 20 - 25 minutes until hot and bubble on the sides. Top with extra bacon and green onions. Serve hot.