Boil water, add peeled potatoes cut into large chunks, cook and drain. Mash or use a ricer. Add a teaspoon of lemon juice or white vinegar to help keep the potatoes from oxidizing and let them cool then cover tightly and refrigerate. Reheat (microwave, crock pot, oven, stovetop) till slightly warm and then add in the liquids (milk, chicken broth, even a little water to rehydrate can work).