1 tablespoon Chocolate Powder (I used Mortimers 70%)
250ml Whipping Cream or Double Cream
2 tablespoons Chestnut Jam
1 tablespoon Brandy
285ml Double Cream
250g Chocolate (I used Green and Blacks 70% Cooking Chocolate, but if you are making this for children you may want to use milk chocolate)
Heat the oven to 170c. Line a large swiss roll pan (at least 15x10 inches) with silicone baking paper.
Beat the whole eggs till thick and light. Whisk the egg whites till they are stiff. Fold the cake mix, water and oil into the beaten eggs and mix gently till fully incorporated. Fold in the egg whites
Spread the mixture into your swiss roll pan and place in the oven
Bake for 15-18 minutes till a fork inserted into the mixture comes away clean.
Sprinkle a little icing sugar over a clean tea towel. I seem to remember I used to use a damp tea-towel, but if the cake is warm enough, there should be plenty of steam from the the sponge itself. Turn the cake onto the tea towel and remove the silicone paper. While the cake is still hot, roll up along the long end. You can help things along by gently cutting into the sponge about 1/4 inch from the edge. Once you have a neat parcel, place on a cooling rack and leave to cool for at least an hour
Cut all the chocolate finely
Heat the cream for the ganache till just below boiling point. Pour the cream over the chopped chocolate and stir until the mixture is smooth and thick.
Cover and refrigerate
When the cake is cool whisk the remaining cream until stiff, fold in the chestnut jam and brandy.
Gently unroll the cake and remove the tea towel. I find it easier to leave the cake half-rolled, rather than flattening and push the cream filling through with a dessert spoon or round bladed knife.
Roll the cake back up and place on a cooling rack with a large board underneath
Once the ganache is cool, coat the cake carefully
Move the cake from the cooling rack to whatever dish you are planning to use to serve from. Use the prongs of a fork to create a 'bark' from the ganache. Sprinkle with icing sugar or decorate with festive ornaments. Or both if you are so inclined.
Covered with a foil tent, this will store well in the fridge for 24-48 hours.