Start with a half dozen fresh sweet potatoes or yams. Cover with cold water and boil until fork tender. Cook and peel. Cut large 1 inch slices into your casserole dish. Melt a stick of butter in a small skillet. Add a cup of dark brown sugar. Stir until sugar is melted and blended well. Add some cinnamon and fresh nutmeg if you desire. Roast some chopped pecans stovetop to bring out that flavor. Sprinkle over the yams. Pour butter mixture over the yams. Cover with large marshmellows and bake 350 for at least 30 minutes.