For this classic dessert I used a raspberry jam flavoured Swiss roll with a simple cream filling. You could just add berries in the cream, change the Swiss roll to be chocolate instead of plain and really experiment with different fillings.
85g caster sugar
35g plain flour
35g potato starch
1 teaspoon baking powder
raspberry conserve for filling
300ml double cream
1 tablespoon caster sugar
2 teaspoons vanilla sugar
3 titanium strength gelatin leaves
For the Swiss roll: Whip the eggs and sugar until pale and thick. Mix the dry ingredients together and add them to the egg and sugar mixture through a sieve. Stir gently until fully mixed. Pour into a large baking tin (about 31cm long, 21cm wide) lined with baking paper and bake in 225C for about 5-7 minutes. Sprinkle some sugar on to a clean baking paper and turn the cooled cake on to it. Let cool completely, spread with raspberry conserve and roll into a tight roll using the baking paper to help.
For the cream jelly: Whip the cream until soft. Add sugar and mix well. Soak the gelatin leaves in cold water for about 10 minutes. In a saucepan, bring milk into boil, squeeze out the water of the gelatin and add them into the milk. Remove from heat and stir until smooth. Add the slightly cooled mixture into the whipped cream, stir well and place in the fridge to settle.
Cut the Swiss roll into 2cm thick pieces. Cover the base of a 1 litre bowl with the pieces, leaving out a couple for the top, and fill with cream jelly. Place the last Swiss roll pieces on top and cover with cling. Put the bowl in the fridge, place some light weight on top and leave to settle for a couple of hours or overnight.