Grate or chop 1x100g bar plain chocolate and 1x100g bar plain chocolate with coffee into a bowl. Add 50ml (2 fl oz) whipping cream and melt over a bain-marie or in a microwave. Stir well, then chill slightly so that the mixture is thickened but not set. Place greaseproof paper on a tray and, using a piping bag with a small nozzle, pipe 20 or so balls onto the tray. Decorate with chocolate-covered coffee beans, almonds, hazlenuts or a sprinkling of cocoa. Put in the fridge to chill.