||Preheat oven to 350 degrees.
Combine flour, brown sugar, and butter with a mixer or a pastry blender until the mixture resembles fine crumbs. Press onto the bottom of an ungreased 9″ x 13″ pan. Place pecans evenly over crust. Set aside.
||Place butter and brown sugar in a small saucepan. Cook over medium heat, stirring constantly. Bring to a boil, and allow to boil for 1 minute (still stirring constantly!). Pour over crust and pecans.
Bake for 16 to 18 minutes or until caramel layer is bubbly. Remove from oven and sprinkle with chocolate chips. After the chips have melted slightly, swirl chocolate over bars.
Cool completely, then cut into bars.