Thanksgiving Yams

Quarter 2 large yams & boil with skins on until tender. Drain & pull skins off. Using potato masher, mash with ½ C. margarine. Spread yams into large greased casserole dish. Mix ½ C. softened butter with 1 C. brown sugar & 1 C. chopped walnuts; sprinkle over yams. Top with single layer of mini-marshmallows. Bake at 350° for 20 min. or until marshmallows are melted.