Pour hot milk over the coffee and set aside to cool completely. Beat very soft butter and sugar until fluffy and light. While beating, start adding one egg at a time, then add half the flour and baking powder. Mix. Add cooled coffee and mix. Add the second part of the flour and mix it. Put the dough into a pan (12 cm wide / 26 cm long / 7 cm high), greased with soft butter and sprinkled with breadcrumbs. Put in the preheated oven to 170 ° C. Bake for about 45 - 60 minutes , to the so-called "Dry stick".

Boil water. In a saucepan, combine the boiling water with instant coffee. Pour a small amount of cold water into the potato flour and shake it into a slurry. Slowly add the flour to the hot coffee and stir it vigorously. Add sugar and butter, let it boil for a while. Pull off the gas. Pierce the cooled down cake with a fork and pour the coffee sauce over it to soak into the centre of the cake.

Finally, prepare the coffee glaze. Heat the cream slightly and mix it with the coffee. Add icing sugar and rub until smooth. Pour the prepared glaze over the coffee cake.