Sift cake flour. Sift powdered sugar.

Make butter smooth. Add the powdered sugar in 3 parts. Mix well with a spatula each time. And then mix it for a minute with a whisk.

Beat egg white lightly so as not to foam. Add it to the butter in 6 parts. Mix each time until it becomes smooth.

Sift almond flour into the batter and mix well. Add vanilla oil and mix well.

Add all the cake flour at once. Fold it. Let it sit in a fridge for 30 minutes. Preheat a oven to 374 ºF.

Take it out of the fridge and mix it gently to soften. Put it in a piping bag. (plain piping nozzle) Squeeze out 24 round shapes on a baking tray.

Hit the tray to flatten batter.

Bake it for 13 minutes at 320 ºF. Open the door and wait 5 minutes as it is. Close the door again and dry it at 230 ºF for 10 minutes.

Cool it well. Put melted chocolate between two cookies.

Let it cool in a fridge for 5 minutes to harden the chocolate. Please store them at room temperature in a sealed container. You should also put a desiccant to keep crispy texture.