I think one of the hardest things for us low carb folks is giving up potatoes and rice. I working on a low carb recipe for the rice but I think this "mashed potato" recipe is good. So good, that I have fooled several carbaholics with them!
If using fresh cauliflower, separate the flowerets. Cut larger pieces to about the size of the smaller pieces. This is very important. You want all the pieces to cook evenly. Steam the pieces until they are soft but not mushy about 8-10 minutes. The microwave works great for this. But check the cauliflower for doneness at 5 minute intervals if you use the micro wave. Overcooked cauliflower has a strong cabbage like flavor and the dish won't taste like mashed potatoes.
Transfer the cooked cauliflower to a food processor. Add cream cheese and butter. Process until smooth. You may have to add a bit of milk but generally the cauliflower has enough moisture. If you add too much liquid the cauliflower will be thin and runny.
Add salt and pepper to taste.. Season salt like Lawry's is great for this dish. If the cauliflower has a strong flavor you may need to add more cream cheese. The cream cheese seems to smooth out the flavor and give you that "potato" taste.
These are great served with a low carb gravy. I made a Shepherd's Pie using these "potatoes". It was sooooo good! I've put them in small oven proof dishes dotted with butter and browned them in the oven. Then I add cheese bacon bits and sour cream to make "twice baked" potatoes.