Growing up, my Mom would always make batch after batch of her famed "Killer Cookie" recipe around the holidays. They were always quick to disappear, and in high demand at family gatherings. It wasn't until years later, when I proudly brought them to a party, that I learned they are actually a pretty common and popular recipe, found on the side of the Eagle Brand sweetened condensed milk can. I'm on to you Mom. Nevertheless, Magic Cookie Bars have remained one of my all time favorite treats to indulge in and share at Christmas time. If you haven't tried them, be warned: they are highly addictive and it's near impossible to stop at just one cookie.