Melt chocolate and keep aside
Beat egg whites with sugar until you get a fluffy texture (using the paddle) then add the rest of the ingredients (including melted chocolate)
Sprinkle caster sugar "topping" on your working surface then roll up the dough to 5mm
Cut to size and place on tray using silicone paper
Let the biscuits dry out overnight uncovered if possible or bake immediately
Bake at 180 degrees for 5 minutes