If you're using skin on almonds, place them in a bowl and pour some boiling water over them, leave them submerged for about 2 minutes. Remove water and peel the almonds by pressing each one between two fingers. Grind almonds in a blender.
Melt the butter for 30 seconds at 800W in the microwawe.
Add grounded almonds, lemon zest, almond syrup and sugar. Mix until combined. Sieve in flour, baking powder and vanilline.
Roughly mix together with a spatula, making sure not to overwork the dough. The dough will and must result pretty crumbly.
Preheat the oven at 180° C (356°F).
Take a portion of dough, place it in the palm of your hand and fist until it holds it shape as shown in the following pictures.
Place the cookies on a baking tray and bake for 15 minutes.
In a bowl combine icing sugar and vanilline.
Once cooked and still hot, toss each cookie in the sugar and vanilla powder and arrange on a grill in order to allow them to cool.
Store the cookies in a cookie box up to 2 months (if they survive that long!).