Drain water completely. Use a ricer if you have one to squeeze the water out of the cauliflower, you can also put it in a clean towel and squeeze it out. Remove as much as possible.
Mash cauliflower as much as desired (I use a potato ricer).
Return cauliflower to the now empty pan on the stove and throw in the rest of your ingredients.
Over a low heat, mix until everything has melted in and the mash is heated through.
Add salt & pepper to taste.
Optional - Go nuts with an immersion blender until it's closer to a puree