Cookie de Savoie: an airy classic from French patisserie

Ingredients

• butter, to grease
• 120 g egg yolk
• 180 g granulated sugar
• 180 g egg white
• 3 g fine salt
• 75 g wheat flour
• 75 g potato starch + extra for sprinkling
• pith from ½ vanilla pod
• 8 g lemon zest
• powdered sugar, for sprinkling

Preparation

1. Preheat the oven to 170 °C. Grease the baking pan with some butter and sprinkle with some potato starch. Pat out the excess starch.
2. Beat the egg yolks with 150 grams of granulated sugar with the (stand) mixer with whisk on high speed until light and fluffy. Spoon into a bowl.
3. Sift the flour and starch twice with a fine sieve into another bowl. To this, add the vanilla and lemon zest.
4. Clean the bowl and whisk of the (stand) mixer thoroughly. Beat the egg whites with the remaining 30 grams of granulated sugar and the salt to stiff peaks on high speed. Be careful not to mix too long, or the egg whites will become flaky.
5. Fold the egg whites into the egg yolks in two parts. Then carefully stir in the flour mixture.
6. Spoon the batter into the baking pan and bake in the oven for 25 minutes, or until the sponge cake is light golden brown.
7. Let the cookie cool in the mold, then carefully remove. Sprinkle the cookie with powdered sugar.