Cherries are normally used in Black Forest cake but we used red currants instead. Why? Our supermarket had run out of canned sour red cherries(!) (We could have gone further afield to search other stores' shelves but it was late, a little cold and we were on our bikes.) While we prefer cherries in the cake, it turns out that red currants are an excellent substitute.
Drain the red currants (or cherries if you have them) and add kirsch. Boil the drained juice with some sugar to make syrup.
Whip heavy cream with a little icing sugar until soft peaks form. Gently stir in kirsch
Because there are only two of us, we make one layer and cut it in half to produce a halfmoon shaped cake. Poke holes in top of the bottom layer with a fork. Drizzle bottom layer with syrup and slather with almost half the cream.
Evenly distribute most of the red currants (or cherries) on top of the cream.
Place top layer on the cream and carefully poke holes with a fork.
Pour remaining syrup overtop.
Slather remaining cream overtop.
Use the remaining fruit to create a design. Run the narrow edge of a rubber scraper on the sides of the syrup pot to draw lines in the cream.
The icing sugar stabilizes the cream so that even the next day, the cream holds its shape. Just in case we hadn't eaten enough, we served this cake after having roast duck a l'orange.