Line the base and sides of a 20cm/8" round deep cake tin with greaseproof paper. Lightly oil and dust with a mixture of 1 tablespoon flour and 1 tablespoon caster sugar.
Beat the eggs with the sugar until thick and pale. Sift the flour with the cocoa powder. Fold gently into the egg mixture one third at a time, adding the water with the last third. Pour into the prepared tin and bake in a pre-heated oven at 190 degrees, gas mark 5 for 25-30 minutes. Leave to cool slightly in the tin, then turn onto a wire rack to cool completely.
When cold, slice the cake horizontally into three layers. Place bottom layer on serving plate, spread with some apricot jam, drizzle half the whiskey (the other half save for the chocolate topping) and cover with half the cream. Cover with second layer of sponge and the remaining cream. Top with the last layer.
At this point you can choose whatever topping you prefer. You can just dust with icing sugar, or cover with the chocolate topping (see below) and garnish with rosettes of whipped cream, chocolate flakes or grated chocolate.
TO MAKE CHOCOLATE TOPPING , break 250 grams (8oz) dark chocolate into a bowl over a pan of hot water, add 1 tablespoon of whiskey, add 15 grams (1/2 oz) of butter and stir until the chocolate has melted. Add one beaten egg and 1 tablespoon of double cream.