This recipe comes via the Brown Eyed Baker, who got the recipe from Cook's Illustrated All-Time Best Recipes. I also found the recipe on cooksillustrated.com, but accessed with my membership, so here's my printer-friendly link.
These bars are very, very good! So good, in fact, that I brought the pan into work today to avoid eating them all myself. My co-workers told me they approve of this method of portion control :)
Although there are quite a few steps in this recipe, it is overall fairly easy to make. Just be sure to allow the full 1 to 2 hours for cooling before moving the foil from the pan to a cutting board.