Overview: Today in the laboratory, four top cookie makers take on one of the hardest technical challenges in the cookie world -- slice and bake cookies! Then, hosts Duff Goldman and Rosanna Pansino reflect on the remaining three cookie makers' creepy 3D haunted mirrors -- each with something spooky trapped inside! Old, haunted mirrors are always cracked, so the cookiers will have to incorporate "cracking" ingredients like kettle chips, pretzels, corn chips and plantain chips. The best mirror-maker will make off with a crackling $10,000.