Step 1

Combine the dry ingredients: In a medium mixing bowl, whisk together the almond flour, powdered sugar, baking powder, and salt.

Step 2

Whip the egg whites: In a large mixing bowl, beat the egg whites with an electric mixer on medium-high speed until stiff peaks form. Add the vanilla extract, almond extract, and lemon zest, and fold to combine.

Step 3

Make the dough: Add the almond flour mixture to the egg whites and fold with a rubber spatula until it comes together into a thick dough.

Step 4

Chill: Cover the bowl and chill in the refrigerator overnight, or at least 4 hours. The dough will keep in the fridge for up to 3 days.

Step 5

Shape the cookies: Remove the dough from the fridge. Dust a work surface liberally with powdered sugar. Use your hands to roll the dough into a 16-inch log, coating it in the powdered sugar. If the dough cracks in places, press it back together and continue rolling. Cut the log into 1/2- to 3/4-inch-thick slices. You should get between 20 and 24 cookies. Lay the cookies flat and use your fingers to shape them into ovals roughly 2 inches long by 1 1/2 inches wide. Place the cookies, spaced about 1 1/2 inches apart, on a baking sheet lined with parchment paper. Dust the cookies generously with powdered sugar.

Step 6

Let the cookies dry: preheat the oven to 350°F. While the oven preheats, let the cookies sit uncovered. The tops of the cookies will dry out slightly, forming a shell that will crack during baking.

Step 7

Bake the cookies: Bake until the tops of the cookies have cracked and the cookies are just beginning to brown, 18 to 20 minutes.

Step 8

Cool the cookies: Let the cookies cool completely on the baking sheet.