1. Preheat the oven to 190C/375F/gas mark 5. Grease 2 x 23cm/9 inch cake tins or spring- release tins with a little butter and line the bases with baking parchment.
2. Melt the chocolate in a small bowl placed over a pan of simmering water. Leave to cool.
2. Finely grind the toasted hazelnuts and breadcrumbs together. Cream the butter and sugar together until pale and fluffy, then beat in the eggs one at a time. Fold in the cooled chocolate then the nut mixture and orange zest.
3. Divide the mixture between the prepared tins and cook in the centre of the oven for about 30 minutes until risen and just firm to the touch. Leave to cool in the tin, then transfer to cooling racks. At this stage the cake can be wrapped and stored in a tin for 2-3 days or frozen for up to a month.
4. For the icing, place the chocolate in a saucepan with 6 tbsp cold water, the cream and sieved jam. Warm gently until the chocolate has melted, then mix thoroughly. Stir in Cointreau. Transfer to a bowl and leave to cool until it has a spreading consistency.
5. For the filling, fold the fruit into the whipped cream and use to sandwich the two cakes together. Put 8 tbsp of the icing into a piping bag fitted with a small star nozzle. Spread the remaining icing over the top and sides of the cake, then pipe whirls of icing around the edge. Decorate with chocolate hearts or red berries if you wish.