When the potatoes are tender, pour off the water off and put them back into the same pan. Using 1/2 head or more, depending on your preference, squeeze the roasted garlic from their skins into the pan. You can save the other half, if not used, as a spread on toast or in a roasted garlic dressing. Add the non-dairy milk to the potatoes and mash by hand or use a hand-held mixer. Add more non-dairy milk as needed if they are too dry. Season with salt and pepper to taste.