In a large mixing bowl, sift together dry ingredients (almond flour, hazelnut flour, powdered sugar, and cocoa powder).

In the bowl of a stand mixer, beat egg whites at medium speed. When the egg whites begin to look frothy, slowly add in the regular white sugar. Increase the speed to medium high and continue beating until a meringue has formed. The meringue should have stiff peaks and appear glossy.

Fold the meringue into the dry ingredients until well combined. The batter will take some time to incorporate and may feel dry at first. The batter should eventually fall like lava from your spatula (similar to a macaron batter). If it isn't getting there, feel free to add in a bit of unwhipped egg whites, a little bit at a time.

Place finished cookie batter into a pastry bag with a large piping tip at the end. Pipe cookies on to a silicone baking mat or wax paper. They will spread out, so make them slightly smaller than you want them to end up.

Bake at 300 for 15 minutes. Remove from oven and allow to cool.