In a large bowl, combine flour, baking powder, and granulated sugar.

Add egg and softened unsalted butter to the bowl.

Knead the ingredients until a homogenous dough forms.

Divide the dough into two portions, with one portion being twice the size of the other (2/3 white, 1/3 for black).

To the smaller portion of dough, add cocoa powder, rum, and sugar.

Knead until the cocoa powder and rum are fully incorporated, creating a black dough.

Roll out the white dough into a rectangle.

Shape the black dough into a log.

Place the black dough log onto one edge of the white dough rectangle.

Wrap the white dough around the black dough log to create an even roll.

Refrigerate the wrapped roll for 60 minutes to allow it to firm up.

Preheat oven to 180°C (350°F).

Remove the roll from the fridge and slice it into 1cm thick disks.

Place the cookie disks onto a baking tray.

Sprinkle brown sugar on top of each cookie disk.

Bake in the preheated oven for 15 minutes, or until golden brown.

Let the cookies cool on the baking tray for a few minutes before transferring them to a wire rack to cool completely.

Serve and enjoy!