Preheat the oven to 400 degrees F. Line a 13 x 17-inch jelly roll pan with parchment paper, lightly greasing above and below the parchment. Preheat the oven to 400 degrees F. Line a 13 x 17-inch jelly roll pan with parchment paper, lightly greasing above and below the parchment.

Whisk egg yolks with half the sugar and a splash of water to form a ribbon. Whisk egg yolks with half the sugar and a splash of water to form a ribbon.

In a stand mixer with the whisk attachment, beat the egg whites and remaining sugar on high speed for one minute. Turn the speed down to medium-low and whisk until the egg whites reach a soft peak (the slower speed will form a more stable meringue). To tell when the whites have reached a soft peak, remove the whisk attachment and hold it with the whisk pointing upwards. The egg whites should form a peak that slightly droops at the top. In a stand mixer with the whisk attachment, beat the egg whites and remaining sugar on high speed for one minute. Turn the speed down to medium-low and whisk until the egg whites reach a soft peak (the slower speed will form a more stable meringue). To tell when the whites have reached a soft peak, remove the whisk attachment and hold it with the whisk pointing upwards. The egg whites should form a peak that slightly droops at the top.

Fold 1/3 of the egg whites into the yolks with a spatula and combine well. Fold in the remaining whites. Fold 1/3 of the egg whites into the yolks with a spatula and combine well. Fold in the remaining whites.

Sift the flour into the egg mixture, folding to combine. Fold in the melted butter. Sift the flour into the egg mixture, folding to combine. Fold in the melted butter.

Pour the batter into the prepared pan. Use an offset spatula to spread the batter evenly. Then, clean around the edge of the pan with your thumb. Note: work gently but swiftly while folding the ingredients together and spreading them in the pan. The air in the whisked egg whites will make this cake very light and spongy, but the moment you begin working with the batter outside the mixer, it will slowly begin to deflate. The sooner it reaches the oven, the more volume your cake will have. Pour the batter into the prepared pan. Use an offset spatula to spread the batter evenly. Then, clean around the edge of the pan with your thumb. Note: work gently but swiftly while folding the ingredients together and spreading them in the pan. The air in the whisked egg whites will make this cake very light and spongy, but the moment you begin working with the batter outside the mixer, it will slowly begin to deflate. The sooner it reaches the oven, the more volume your cake will have.

Bake for 7-10 minutes, until the cake is golden and spongy on top. Bake for 7-10 minutes, until the cake is golden and spongy on top.