Sponge Cake (Bizcocho de Espuma)

Ingredients

• 12 whole egg yolks
• 250 grams sugar
• 12 whole egg whites
• 120 grams flour
• 90 grams potato starch
• vanilla

Instructions

1. Whisk the egg yolks with the sugar very thoroughly until well combined. In a separate bowl, whip the egg whites to stiff peaks (merengue). Fold the whipped whites gently into the yolk mixture, combining everything well. Sift together the flour and potato starch, then fold these into the egg mixture. If desired, flavor with vanilla. Transfer to a prepared baking pan and bake in a moderate oven for just over fifteen minutes, until set and lightly golden.