Mix flour, 1 cup brown sugar and 1/2 cup butter at low speed. Pat into the bottom of a (greased) 9x13 inch pan.
Sprinkle pecans over the top.
In a saucepan, boil 1/2 cup brown sugar and 2/3 cup butter for 1 minute. Pour over crust/pecans.
Bake in a 350 degree oven for 18-20 minutes or until bubbly.
Remove from oven let set for 2-3 minutes. Sprinkle chocolate chips over cookies. Let melt. Swirl over the top. Cut into bars when set.
HINT: To remove bars from baking pan easily line pan with aluminum foil. Grease the foil. Bake bars in foil. I do this with most bars cookies. I then lift them out onto my cutting board. This was I can cut even bars and place in tins.
NOTE: I made these this weekend and grab a bag a Nestle semi-sweet choco chips accidently. I prefer milk choco chips. Also I prefer less chocolate and when not in a hurry I like to buy a couple bars of good milk chocolate. Melt that and drizzle it on the bars. They look very pretty this way and you can enjoy the taste of the pecans vs. chocolate!