Melt chocolate chips entirely. Stir in mashed potatoes. Add vanilla and stir, stir, stir. Place mixture in refrigerator to firm up for about 30 minutes. Take 1 tablespoon-sized pieces and roll between palms of your hand to make a ball. Roll into desired topping(s) and place on a baking sheet. Return to refrigerator until firm. Will keep one week in refrigerator.