Overview: Man on the Street John “Doc” Willoughby heads to the Mast Brothers Chocolate Factory in Brooklyn to learn all about the art of chocolate making. Next, test cook Bridget Lancaster shows host Christopher Kimball how to make perfect Chocolate Truffles at home. Then, tasting expert Jack Bishop challenges Chris to a tasting of cocoa powder. And finally, test cook Julia Collin Davison reveals the secrets to making the best French Apple Cake.