1Combine flour, 1 cup brown sugar and softened butter in large mixer bowl. Beat at medium speed of electric mixer 2 to 3 minutes or until mixture resembles fine crumbs. Pat mixture evenly onto bottom of ungreased 13 x 9 inch baking pan. Sprinkle pecans evenly over crumb mixture.
2Combine 2/3 cup butter and remaining 1/2 cup brown sugar in small saucepan. cook and stir over medium heat until entire surface is bubbly. cook and stir 1/2 to 1 minute more. Pour into pan, spreading evenly over crust.
3Bake in 350 degrees F (175 degrees C) oven 18 to 20 minutes or until entire surface is bubbly. Remove from oven; immediately sprinkle with chocolate pieces. Let stand 2 to 3 minutes to allow chocolate to melt; use knife to swirl chocolate slightly. Cool completely in pan on wire rack. Use sharp knife to cut into 48 bars.
Footnotes
Tip
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.