Use mixer or processor fitted with metal blade to cream sugar and butter. Add eggs and mix until thick and flowing. Add melted chocolate, cocoa, water and vanilla. Mix well to combine. Transfer to mixing bowl if using processor. Stir in flour, salt, walnuts and milk chocolate pieces until well combined. Transfer batter to lightly greased and floured 9-inch square aluminum pan. Bake an center rack of 325-degree oven until wood pick inserted in center comes out without uncooked dough sticking to it, about 20 minutes. Do not overbake. Brownies will not have pulled away from sides of pan. Remove from oven. Immediately arrange marshmallows in single layer over hot brownies. Bake 1 minute longer. Let cool on rack. To cut brownies into neat squares, dip sharp knife often into hot water. Makes 16 (2-1/4 inch ) brownies. Each brownie contains about: 221 calories; 34 mg sodium; 40 mg cholesterol; 13 grams fat; 25 grams carbohydrates; 3 grams protein; 0.37 gram fiber. cook 026 cook 043