In a medium size bowl, sift powdered sugar and almond flour. Using a whisk gently mix them together with graham cracker and set aside.
Using a stand or hand mixer begin to beat the egg white in a large bowl. The stand mixer bowl will be just fine. Gradually increase the speed until it is on high.
When the egg white begins to froth, add the granulated sugar and continue mixing until you achieve stiff peaks.
In two batches gently begin to fold in the dry ingredients. I prefer the scrape and turn the bowl method but do whatever suits you. However, be careful to not over mix.
Fill a piping bag with a small round tip.
Line the baking sheets with silicone baking mats. Begin piping the shells leaving about an inch between each. Try to make them the same size to the best of your ability or use a guide.
Once you have piped the shells, give the baking sheet a few good smacks on the countertop or floor. I’m serious about this step. It helps release all the air bubbles so you can get those nice feet on the shells.
Let your shells sit for about 30-60 minutes until they form a stiff exterior. You’ll know they are ready when you gently touch them and no batter is left on your finger. The length of time will depend on the temperature of your kitchen.
Once they are ready, bake them in a preheated oven at 300 degrees for 16-18 minutes.
When the shells are baked, let them be. When the silicone mat is cooled enough to touch, move the entire mat with the shells onto a cooling rack. When they are fully cooled, they can be removed and are ready for assembly.