For this week's Quickfire Challenge, the chefs must create a dish with an ingredient using only the toughest stains as their clues. Then, in a high-stakes pizza party, the chefs must create pies that are outside of the box to impress guest judges Michelin star chef Wylie Dufresne and Top Chef All-Star alumn Spike Mendelsohn, who join Kristen, Tom and Gail at the judges' table.