Step 1

Preheat the oven to 180°C/fan160°C/gas Line the sides and base of a 24cm x 35cm swiss roll tin with baking paper, so that the baking paper comes up above the rim of the tin.

Step 2

Make the swiss roll. Place the white chocolate in a bowl, suspend it over a pan of barely simmering water and allow to melt slowly. Remove the pan from the heat and leave to cool a little.

Step 3

Crack the eggs into a large bowl and add the almond essence and sugar. Whisk for about 10 minutes until pale and thickened (the whisk should leave a trail when moved through the mixture). Carefully fold first the melted chocolate into the mixture, then the flour.

Step 4

Pour into the lined tin and bake in the oven for 15-20 minutes until spongy to the touch. Meanwhile, place a large sheet of baking paper on a work surface and dust with caster sugar.

Step 5

Remove the cooked sponge from the oven and quickly flip the tin over onto the sugared paper. Remove the tin, then carefully peel away the paper from the base of the sponge. Loosely roll up the sponge and sugared paper together, from the short end. Leave to cool completely.

Step 6

For the filling, slowly melt the chocolate as in step 2, then allow to cool a little. In a large bowl, lightly whip the double cream with the scraped vanilla seeds, then fold through the melted chocolate. Unroll the sponge and spread over the chocolate and cream mixture, leaving a 1cm border. Scatter over the raspberries before carefully re-rolling the sponge (without the paper). Allow to cool completely.

Step 7

Wrap tightly in more baking paper, then cling film, and freeze for up to 3 months. Defrost thoroughly before serving in thick slices.