I got this from Bakerella, except she calls them Congo Bars. This was my first attempt, pretty easy recipe to follow
The amount of sugar is ridiculous, a lb of brown sugar is about 2 1/4 cups worth...so if you would like to cut it down, I'd recommend 1 3/4 cup. Mine were in the oven for 45 minutes. It was soft and gooey, (but not falling apart) with crisp edges. Made them for a movie night and they were gone before the movie was over.
Recipe from here: http://www.bakerella.com/i-hope-you-have-chocolate-chips-handy/