Cook cauliflower in one cup of water on medium high heat on the stove top. Cover pan.
Stir every five minutes or so to help the cauliflower cook evenly. After about 15 minutes test a couple of the biggest pieces out of the pan. Cut them in half. If they're warm, they're done. If they are cool, continue to cook for additional 5-minute increments until just cooked.
Drain the water from the pan and add sour cream, half of each of the cheese and half of the bacon. Stir well and place in a greased 9 x 13 casserole dish.
Sprinkle remaining cheese and bacon on top. Bake for 15 minutes at 350º F. Add chopped green onion on top and enjoy!