Cut cauliflower into florets and discard or save the stems. Steam for 10-12 minutes until fork tender. Do NOT overcook or the end result will be mushy, if you undercook it the "mashed potatoes" will be grainy. Check the cauliflower at 10 minutes to see what the texture is, if a fork can pierce it easily then it's done.
Drain any excess liquid from your cooked cauliflower (I use a steamer basket) then add to the bowl of a food processor along with the Earth Balance/Butter/Oil and blend until completely smooth. Do not add liquid though, keep processing! You may need to stop and stir a couple times, it may take 5 minutes depending on your processor and amount of veg in the bowl.
Season (generously) with pepper and garlic salt (my preference) or sea salt to taste. Transfer to a mixing bowl and stir in mix-ins OR divide portions into bowls and top with "mix-ins" and serve! If you are adding salty add-ins such as bacon, sausage or cheese afterward, add some salt at the beginning and re-taste after mixing in ingredients.