Place the egg whites in a bowl and beat them with a pinch of salt until stiff peaks form.

In a separate bowl, mix the almond flour with the sugar. Gradually add the orange and lemon zest. Gently fold in the beaten egg whites, mixing carefully from bottom to top.

On a baking sheet lined with parchment paper, shape the dough into diamond-shaped cookies to form the classic ricciarelli shape.

Transfer the ricciarelli to a preheated oven and bake for 8–9 minutes at 350°F (180°C), making sure the cookies do not brown on top.

Let cool, then dust with vanilla powdered sugar.