Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

Separate the egg yolks and whites. In yolks bowl, mix in half the sugar and whip until pale and fluffy, about 3–5 minutes. Add vanilla extract and optional lemon zest.

In another bowl, whip egg whites on medium speed, gradually adding remaining sugar until stiff peaks form, about 4–6 minutes.

Gently fold whipped egg whites into the yolk mixture, then gradually fold in sifted flour and cornstarch until no flour streaks remain.

Transfer the batter to a piping bag. Pipe 3-inch-long and 1-inch-wide fingers onto prepared baking sheets, leaving space.

Lightly dust piped cookies with powdered sugar and bake for 12–15 minutes until golden and puffed.

Cool cookies on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.