This recipe is from Cook's Illustrated and I made them today and it is fabulous! I omitted the pepper but stuck by the rest of the recipe. "Cutting the sweet potatoes into slices of even thickness is important in getting them to cook at the same rate. A potato masher will yield slightly lumpy sweet potatoes; a food mill will make a perfectly smooth puree. The potatoes are best served immediately, but they can be covered tightly with plastic wrap and kept relatively hot for 30 minutes. This recipe can be doubled in a Dutch oven; the cooking time will need to be doubled as well."