Bring a pot of water to a boil and lower the eggs into the pot. Boil the eggs for 8-10 minutes, then remove the eggs and put them in an ice bath to cool. Once they have cooled, peel off the shells and separate the whites from the yolks. Set the whites aside to use for another purpose.
Next, sift the flour, cornstarch and powdered sugar into the bowl of a food processor. Add a pinch of salt and the lemon zest and pulse the mixture until the ingredients are combined.
Press the egg yolks through a fine mesh sieve and add to the bowl of the food processor. Then, add the cubed butter and vanilla extract.
Blitz the mixture until the dough is almost combined. Then, transfer the dough to a large work surface and knead until it comes together. Wrap the dough in plastic wrap and allow it to rest for an hour before continuing.
Once the dough has chilled, preheat the oven to 350°F. Then, place the dough on a lightly floured, work surface. Place a piece of parchment paper over the top of the dough, and using a rolling pin, roll it to about 1/3″ in thickness.
Use a flower shaped cutter to cut out the cookies and use a small round cutter to make the hole in the center.
Lay the cookies on a parchment lined baking sheet and bake at 350°F for about 10 minutes. Do not allow the cookies to brown.
When they are done, allow them to cool on the baking sheet for a few minutes and then transfer to a drying rack to cool completely.
Dust with powdered sugar and enjoy!
