In large bowl, whip egg whites until foamy; add cream of tartar and beat until soft peaks form when the beater is raised. Gradually add remaining tablespoon of sugar; beat until stiff peaks form. With a spatula, gently fold 1/3 of the egg whites into the egg yolk mixture to lighten. Add remaining egg whites and fold in until there are no remaining streaks of flour, and the eggs are well incorporated. Gently spoon batter into prepared pan, filling cavities about 1/2 full. Do not smooth tops.