Melt 50 g (2 oz) of the chocolate and the butter in a heatproof bowl set over a saucepan of gently simmering water (don't let the base of the bowl touch the water).
Beat the eggs, sugar and vanilla in a separate bowl until light and foamy. Stir in the melted chocolate mixture. Tip in the flour, cherries and remaining chocolate and mix together until just combined.
Spoon the mixture into a greased and lined 18 cm (7 inch) square cake tin or shallow baking tin (see
Whip the cream in a bowl until peaking, then spread over the cake. Sprinkle with chocolate shavings and cut into small squares. Serve with extra cherries and Rich Chocolate Sauce, if liked (see below).