• Preheat the oven to 180ºc/Gas 4. Grease a swiss roll tin 23cm x 33cm and line with baking paper. 
• Melt the chocolate over a pan of gentle simmering water, then leave to cool.
• Place the egg whites in a large grease-free bowl and using an electric whisk, whisk them until they form soft peaks.  Set aside.
• Place the egg yolks and sugar in a large bowl and whisk until the eggs are fluffy and thick enough to leave a trail when the whisk heads are lifted from the mixture.
• Stir in the cooled chocolate until fully combined and then gently fold in the egg whites.
• Once all combined, pour into the swiss tin and gently level, then bake in the oven for 20 – 25mins, until firm to the touch.  Remove the cooked sponge from the oven and leave to cool in the tin.
• To make the filling, whip the cream and icing sugar until it forms soft peaks and set aside.
• Lay a clean tea towel on the surface (this will help give extra grip while rolling up the sponge) and cover with a sheet of baking paper, dusted with icing sugar.  Turn the sponge out onto the dusted baking paper and gently peel off the lining paper.  Spread the sponge with the cream, then gently place the raspberries all over (leaving a couple for decoration).
• Using the tea towel and baking paper, roll up a tightly as possible, like a swiss roll. You will see some lovely cracks appearing as you do this, this is perfect so don't worry.
• To finish, dust (with a tea strainer) some icing sugar over the top, add a couple of raspberries on top and then enjoy.

Top tip

• If there is any left over, this pudding freezes really well.