In heavy 2-quart saucepan over medium heat, cook sugar and evaporated milk, stirring constantly until sugar is dissolved and mixture boils; boil 5 minutes, stirring constantly. Remove from heat; stir in marshmallows and chocolate chips until melted and mixture is smooth. Add chopped walnuts; continue to stir until mixture is thickened. Pour into 8-inch-square baking pan; let stand about 10 minutes until top is firm to touch. With tip of sharp knife, score top of fudge in approximately 1-1/2-inch squares to make 25 squares; gently press walnut piece into center of each square, if desired. Refrigerate about 30 minutes until firm. Cut into squares along score marks. Store in covered containers in cool dry place for up to 2 weeks. Makes 25 pieces. candy 02