Yam & Sweet Potato Souffle Recipe

Preheat oven to 350. Cut yams and potatoes crosswise into even pieces about 2 inches long and boil in jackets until just tender. Do not over cook or they will fall apart. Cool and remove the skin. Heavily butter an 8-cup souffle dish. Alternate thin layers of yam and potato slices seasoning each layer with juice, zest, brown sugar and pats of butter until dish is half full. Rice the remaining yams and yellow sweet potatoes (omit any purple potatoes from this step) and stir in the eggs yolks and melted butter. Season the soufflé base with juice, zest, salt and white pepper to taste. Fold in the stiffly beaten egg whites and top souffle dish. Bake 45 - 50 minutes until firm and lightly browned.