1. Preheat the oven to 180°C, Gas Mark 4. Cut a rectangle of non-stick baking paper a little larger than a 34 x 23 cm (131/2 x 91/2 inch) Swiss roll tin or roasting tin with the same base measurement. Snip diagonally into the corners of the paper then press into the tin so that the base is lined and the paper stands a little above the sides of the tin.
2. Melt the chocolate in a bowl set over a saucepan of very gently simmering water. Using an electric whisk, whisk the egg whites until peaking. Using the still dirty whisk, whisk the egg yolks and sugar together in a second bowl for 4-5 minutes until thick and pale and the mixture will leave a trail.
3. Fold the melted chocolate into the egg yolk mixture then the hazelnuts and water. Fold a little of the egg white into the mixture to loosen it then gently fold in the rest.
4. Spoon into the tin and lightly ease into an even layer. Bake for 15 minutes until well risen and the top is slightly crusty. Leave to cool covered with a clean teacloth. Add the blackberries and liqueur to a bowl, cover and leave roulade and berries to stand for 3-4 hours, or longer if that suits you better.
5. About 2-3 hours before serving, whip the cream until it forms soft swirls then fold in the icing sugar and the liqueur from the soaked blackberries.
6. Wet a clean teacloth under a hot tap, wring out and put on the work surface so that the shorter edges face you. Top this with a clean sheet of non-stick baking paper and sprinkle with a little extra sugar. Turn the roulade out on to the sugared paper and remove the lining paper.
7. Spread the cream over the roulade, sprinkle with the soaked blackberries then roll up the roulade starting from the short edge nearest you and using the paper and damp teacloth to help. The roulade will crack, but don’t worry, just continue rolling and pressing into a good shape until you reach the other end. Wrap the paper and cloth around the roulade for a few minutes to set the shape. (If you would like to serve this for Christmas day, wrap the roulade in paper and foil and keep in the fridge overnight) Remove the paper and cloth and transfer the roulade to a serving plate. Decorate with chocolate holly leaves (see tip below) and extra blackberries.
For the Chocolate holly leaves:
1. Snip about 20 holly leaves from a small branch, leaving just a little of the stem on. Wash and dry the leaves then brush the shiny top of each leaf with a little melted chocolate leaving a little of the leaf and stem uncovered. Put leaves on a baking sheet lined with non-stick baking paper, chocolate side uppermost and chill in the fridge until the chocolate has set. Cover with a second thin layer of melted chocolate (you’ll only need about 75g (3oz) of chocolate in all) and chill again. When ready to use, hold the stem end of the leaf and very gently begin to peel and curl the leaf away from the chocolate. Arrange on the top of the roulade.
Recipe courtesy of Seasonal Berries