Mix the cocoa with the sugar, then add and stir the eggs.

When it's well mixed up, add the potato flour, the melted butter, the coffee and finally the rum.

When it becomes creamy, put it in a circular tin (diameter ~ 28 cm) after smearing it with some butter.

Bake it in the oven for 25 minutes at 160°. After leaving it in the closed oven for about 5 minutes, you can take it out and enjoy it.