"[Photographs: J. Kenji Lopez-Alt] Note: because of variation in the shape of potatoes, the amount of potato that will fit into a single casserole dish varies. Longer, thinner potatoes will fill a dish more than shorter, rounder potatoes. When purchasing potatoes, buy a few extra in order to fill the dish if necessary. Depending on exact shape and size of potatoes and casserole dish, you may not need all of the cream mixture. About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook. Every recipe we publish is tested, tasted, and Serious Eats-approved by our staff. Never miss a recipe again by following @SeriousRecipes on Twitter!..."