Preheat the oven to 350°F—line sheet trays with parchment paper and set aside.
Whisk together the sifted flour and cornstarch until combined in a medium bowl.
1 cup all-purpose flour, 2 tablespoons cornstarch
Whisk the eggs, sugar, and salt well in a heatproof medium-sized bowl.
3 large eggs, 2/3 cup granulated sugar, 1/4 teaspoon kosher salt
Place the bowl over a double boiler over medium heat, whisking constantly and scraping the sides and bottom.
Continue to do this until the internal temperature of the mixture reaches 165°F. This is a very important step; it can take 5-15 minutes for the eggs to reach the correct temperature.
Add the egg mixture and vanilla to the body of a stand mixer with the whisk attachment.
1/2 teaspoon vanilla extract
Whip the egg mixture on high until light and fluffy and making medium peaks. You know it is ready when a dollop of it stays for a second and then sinks back into the mixture. This step will take 5-8 minutes.
Fold in the sifted flour and cornstarch until just combined; do not over-mix.
Using a piping bag with a 1/2-inch tip, pipe cookies onto parchment paper about 3 x 1/2 inches in size and one inch apart. You can also make them as long as you like.
Generously sift powdered sugar on top. Bake for 12 minutes, until they are very lightly golden around the edge.
1/4 cup powdered sugar
Let them cool for 2 minutes on the baking sheet, then transfer to a wired rack to cool completely.
Notes
These can be frozen, read my storing tips above.
Vanilla bean paste can be hard to find, you can swap out with regular vanilla for this recipe.
Make sure you constantly whisk your egg mixture, this will keep it from overcooking.
Make sure you do not over mix the batter of this recipe, it will dry them out, gently fold in until you see no more dry patches.
If you do not own a piping tip, just cut off the tip of your bag so they can reach the 1/2″ wide thickness.
These will spread slightly while cooking, this is normal.
Do not worry about dusting more powdered sugar on the pan, this will not burn.