Method:

• Heat oven to 350ºF. Spray 8-inch round cake pan with cooking spray. In small bowl, stir cake meal, potato starch and nutmeg until well mixed; set aside.
• In large bowl, beat egg whites with electric mixer on high speed until soft peaks form. Gradually beat in 1/4 cup of the sugar until stiff, but not dry, peaks form.
• In another small bowl, beat egg yolks slightly. Gradually beat in remaining 1/4 cup sugar on medium speed about 5 minutes or until mixture is thick, lemon-coloured and forms a ribbon when beaters are lifted. Stir in bananas, oil and lemon peel.
• Fold banana mixture into beaten egg whites. Sift half of cake meal mixture over batter; gently fold in. Sift and fold in remaining cake meal mixture. Fold in walnuts. Spoon batter into sprayed pan, smoothing top.
• Bake 25 to 27 minutes or until golden brown and toothpick inserted in centre comes out clean. Loosen from sides of pan with metal spatula; turn out onto cooling rack. Cool completely. To serve, cut into wedges; sprinkle with icing sugar.