2 c. all-purpose flour
1 c. firmly packed brown sugar
1/2 c. butter

In large mixer bowl combine above ingredients. Beat at medium speed, scraping bowl often, until well mixed and particles are fine (2-3 minutes). Press on bottom of 13x9 inch baking pan. Sprinkle with 1 cup pecan halves.

In saucepan combine: 1/3 c. brown sugar

Cook over medium heat, stirring constantly, until mixture comes to a full boil. Boil, stirring constantly, until mixture reaches 242 degrees (about 1 minute). Pour evenly over pecan and crust. Bake 18-22 minutes or until entire caramel layer is bubbly. Remove from oven. Immediately sprinkle with 1 cup semi-sweet chocolate chips. Allow to melt slightly. Swirl chips leaving some whole for a marbled effect. Cool completely; cut into 3 dozen bars.