In the bowl of a mixer, beat egg whites with the whisk attachment until semi-soft peaks begin to form. Gradually whisk in 1/3 cup of the remaining sugar and continue beating until stiff peaks finally form. Remove and carefully fold in yolk mixture. Combine dry ingredients. Fold dry ingredients, followed by melted butter.
Pour batter into prepared pan. Bake cake for 12 minutes or until cake gently springs back when touched. After removing the cake from the oven, and immediately sprinkle with powdered sugar. Carefully turn the cake out onto a clean towel that has been dusted with powdered sugar.