Butter 15x10x1-inch baking pan; set aside.

Combine all ingredients except nuts and chocolate chips in heavy 3-quart saucepan. Cook over medium heat, stirring constantly, until butter is melted.

Reduce heat to medium-low. Cook 25-40 minutes, stirring occasionally, until candy thermometer reaches 300°F or small amount of mixture dropped into cold water forms hard brittle strands. Stir in 1 cup nuts.

Pour mixture into prepared pan; spread to desired thickness. Sprinkle chocolate chips over hot candy; let stand 5 minutes. Spread melted chocolate evenly over candy. Sprinkle with nuts. Cool at least 3 hours. Break into pieces.