You will never miss the calorie-laden cream in this fresh take on a favorite winter soup. Substituting a potato for the usual half-and-half or heavy cream gives this rich, full-bodied cauliflower soup a velvety texture without adding more fat. Go ahead and add the cauliflower stem to the pot-it has great flavor and will be blended along with the florets. Serve with a tossed salad or your favorite hearty sandwich. If you want to make this recipe completely dairy free, replace the butter with olive oil.