I love mashed potatoes, and so do my children! I've finally come up with a mashed potato that is acceptable to me without all the problematic dairy (my 'regular' mashed potatoes have butter, heavy cream and sour cream in them...)!
MSPI safe margarine or clarified butter (if tolerated)
MSPI safe chicken broth
MSPI safe non-dairy creamer (original flavor)
Scrub potatoes (peel or don't peel...your preference) and boil in just enough water to keep from scorching. When tender, drain any remaining water from the pot. Mash the potatoes (dry), then add some chicken broth and garlic salt. You want them definitely thick. Add a knob of margarine or clarified butter, stirring until the margarine or clarified butter is melted. Finish with enough non-dairy creamer to your preferred consistency. Season to taste with salt, pepper, and additional garlic salt if desired.