Preheat oven to 180 degrees C. Line a 23cm round cake tin with baking paper, grease with butter and sprinkle with cocoa.
Sift together the flour and cocoa. Beat the eggs with half the sugar until light and fluffy. Stir into the flour. Add the melted butter and stir well.
Pour batter into the cake tin and bake 30 minutes. Let cool completely, then slice in half horizontally. Combine the cherry liqueur and water and sprinkle half over the bottom half of the cake.
Make the filling. Dissolve the gelatine in a minimum amount of boiling water and cool slightly.
Whip the cream until stiff, adding the icing sugar near the end. Spread over the bottom half of the cake. Push cherries into the cream, then top with the other half of the cake. Sprinkle over the rest of the cherry liqueur and place in the fridge.
In a mixing bowl over a saucepan of simmering water, melt the butter and chocolate together, stirring. Let cool slightly.
Remove the cake from the fridge and spread over the icing. If you like, garnish with grated chocolate, whipped cream and cherries.