To begin with, I use soy cream instead of dairy-based cream.  It tastes alright, but not superb, and it seems to require more salt. What is missing that I should find a substitute to add back in? 
I made some this past week with a little olive oil (maybe 1 tablespoon?) and a little almond milk (maybe 1 teaspoon?). (I am unable to eat dairy.) I also had a rutebega mashed in--one rutebega to 4 Russet potatoes. It was delicious and even my husband, who can eat all the dairy he wants, thought they were just fine. 