make the cookie dough
In a small bowl combine all purpose flour, unsweetened cacao powder, baking powder and pinch of salt. In a large bowl (or in a bowl of a stand mixer) cream together the sugar, brown sugar and butter to get a nice, creamy mixture. Optionally add a teaspoon of vanilla extract. Mix for about 5 minutes. Add one egg at a time, beating after each addition. While mixing, pour in the melted chocolate. Gradually mix in the milk and dry ingredients until completely incorporated. Optionally mix in one tablespoon of rum for flavor.
Place in a fridge or freezer
Divide the dough in half and wrap in cling film. Place in a fridge for 2 - 3 hours, or overnight or place in a fridge for 1 hour. That way the cookie dough will be easier to work with.
Shape into cookies
Preheat your oven to 180 °C / 350° F. Combine sugar and icing sugar in a small bowl or in a deep bowl. Between your hand roll the dough in a walnut sized ball. (approx. 3 cm in diameter or 20g). Roll the ball in the sugar mixture and place on a large baking sheet, lined with parchment paper. Make sure to leave enough space between each cookie, because they will spread.
Bake and Serve
Place the baking sheet with cookies in your oven and bake for about 12 minutes at 180 C / 355 F. Transfer baked chocolate crinkle cookies to a wire rack to cool. Serve or store in a cookie box for up to 14 days.