America's Test Kitchen Season 21, Episode 17 : Bake Sale Favorites

Host Bridget Lancaster bakes celebration-worthy Yellow Sheet Cake with Chocolate Frosting, ingredient expert Jack Bishop gives a primer on the world of dark chocolate, and gadget critic Lisa McManus shares her favorite gear for baking cookies. Finally, test cook Erin McMurrer harnesses the power of science to make the best Chewy Peanut Butter Cookies.