• Preheat the oven to 350°F/180ºC. Line two large baking sheets (or three small baking sheet with non stick parchment paper.
• Separate the eggs, putting the egg yolks into a small bowl for later.
• Beat the egg whites with an electric mixer with the whisk attachment until stiff peaks.
• Gradually add the sugar and continue beating until the sugar is dissolved and the mixture is thick and glossy.
• Mix the lemon zest and vanilla extracts into the egg yolks.
• Use a spatula to combine the egg yolk mixture with the egg whites until just incorporated.
• Sift the cake flour, cornstarch and salt over the egg mixture.
• Use a spatula to gently fold the dry ingredients in until just mixed. It is important to fold very gently to not to deflate the batter meaning that the savioardi would be flat and not as spongy. The mixture will deflate a little but that's fine - you've got a lot of air into those egg whites.
• Use a piping bag with a plain ½ inch (1.5cm) tip (or you could just snip the end off, or use a ziplock bag filled with the batter.
• Pipe the batter into 5 inch (12cm) lengths leaving space between each to allow for spreading.
• Sift half of the powdered sugar over the savoiardi and wait for 5 minutes. The sugar will melt and look wet. That’s what it’s meant to do.
• After 5 minutes, sift over the remaining powdered sugar. You may need a little bit more. Sprinkling with powdered sugar is what creates the characteristic crust of savoiardi.
• Bake savoiardi cookies for 10 minutes, then rotate the baking trays and bake for another 5 minutes.
• Allow to cool for 5 minutes then remove with a metal spatula while still warm and cool on a wire rack.
• Store in an airtight container.

For dry, crispy savoiardi similar to store bought

• This is what I do using an electric oven.
• Switch off the oven and allow it to cool down for two hours or until under 200°F (100ºC). Place savoiardi back on baking trays and return to the turned off oven overnight or until dried and crispy.