1½ lbs unpeeled whole yams
2¾ C sugar
¾ C water
6 large egg
1 T vanilla extract
¾ tsp salt
2 C whipping cream
2 tsp grated orange peel
Cook sweet potatoes in large pot of boiling water until tender, about 35 minutes. Drain well. Let cool 20 minutes. Peel potatoes. Transfer to medium bowl; mash until smooth. Set aside.
Preheat oven to 325°F and position rack in center of oven.
Stir 2 C sugar and ¾ C water in heavy medium saucepan over medium heat until sugar dissolves. Increase heat and boil without stirring until syrup turns deep amber, occasionally brushing down sides of pan with wet pastry brush and swirling pan, about 10 minutes. Working quickly, divide caramel amoung twelve ¾-cup soufflé dishes or custard cups, tilting cups to cover bottom with caramel. Cool.
Whisk mashed sweet potatoes, remaining ¾ C sugar, eggs, vanilla and salt in large bowl to blend well. combine cream and orange peel in heavy medium saucepan. Bring to boil. Gradually whisk cream into potato-egg mixture. Strain mixture into 2-quart measuring cup or bowl; discard solids in strainer. Divide mixture among custard cups. Place 6 cups in each of 2 large baking pans. Add hot water to baking pans to halfway up sides of cups.
Bake flans until sides are set but center still moves slightly when cups are shaken. Remove cups from water and cool about 40 minutes. Cover and refrigerate at least 2 hours (can be made 2 days ahead if kept refrigerated). Run small sharp knife around edges to loosen. Turn flans out onto plates and serve.
Source: Bon Appétit Magazine November 2000