Mash sweet potatoes while they are hot, then add, butter, salt, and spices. Add egg and continue to whip until thoroughly combined. Chill until firm. Form into golf ball sized pieces and place 2 to 3 marshmallows in center of each ball. Roll in ginger snap crumbs. Place on non-stick or lightly greased baking sheet. Bake for 10 to 15 minutes.