In a large mixing bowl, combine cold butter, brown sugar, and flour. Mix until crumbly, then press into the bottom of a greased baking pan.

Preheat oven to 350°F (175°C). Bake crust for 15-20 minutes until lightly golden.

In a saucepan, heat caramel sauce over low heat, stirring frequently. Mix in chopped pecans.

Pour the caramel-pecan mixture over the crust and spread evenly.

Melt chocolate chips with a small amount of butter in a microwave-safe bowl, stirring until smooth.

Spread melted chocolate over the caramel layer quickly before it begins to set.

Allow bars to cool at room temperature for at least 30 minutes before chilling in the refrigerator.

Once cooled, cut into squares or rectangles and serve.