Butter two (15x10x1-inch) baking pans and set them aside.

Combine sugar, butter, water, and corn syrup in a heavy pan. Cook over medium heat, stirring constantly, until butter is melted.

Reduce heat to medium-low and cook for 25-40 minutes, stirring occasionally, until a candy thermometer reaches 300°F or a small portion of the mixture dropped into cold water forms hard brittle strands. 

Stir in 1 cup of the chopped nuts.

Pour mixture evenly into prepared pans; spread to your desired thickness. 

Sprinkle 1 cup of chocolate chips over each pan and let stand for 5 minutes before spreading the melted chocolate evenly over the candy. 

Sprinkle with the remaining ½ cup of nuts. Cool for at least 3 hours. 

Break into pieces.

Store in an airtight container in a cool dry place, for up to 3 weeks.