In small mixing bowl beat egg yolks at high speed until thick and lemon-colored, about 5 minutes. Blend small amount of hot sweet potato mixture into yolks. Blend yolk mixture into potato mixture. Stir in lemon peel and mace.
Wash and dry beaters. In large mixing bowl beat egg whites and cream of tartar at high speed until stiff but not dry, just until whites no longer slip when bowl is tilted. Gently fold yolk mixture into whites. Pour into prepared dish. Sprinkle with pecans, if desired. For a “top hat,” hold a spoon upright and circle mixture to make a ring about 1 inch from side of dish and 1 inch deep.
Bake in preheated 350° F. oven until puffy, browned and souffle shakes slightly when oven rack is gently moved back and forth, 50 to 60 minutes. Carefully remove foil band. Serve immediately.
SPINACH SOUFFLE
6 servings
Grated Parmesan cheese
1 (10¾ oz.) can condensed cream of chicken soup
1 (10 oz.) pkg. frozen chopped spinach cooked and well-drained
½ C. shredded Cheddar cheese
1 T. instant minced onion