Chop dark chocolate.
Melt chocolate and unsalted butter in a bowl and stir with a spatula until combined.
Add cacao, granulated sugar, vanilla sugar, all purpose flour and light syrup and combine using a spatula.
Add egg and combine using a spatula.
Let the batter cool in the fridge for 30 min.
Preheat the oven to 175 C and place parchment paper on a baking sheet.
Take about 1-2 tbsp of the batter and place it on the parchment paper. Repeat with remaining batter.
Bake in the oven for about 8-9 min, sprinkle some sea salt over them, then let them cool down completely on a wire rack.
