150 g (5 oz) white chocolate, broken into small pieces
150 ml (1/4 pint) crème fraîche
To make the chocolate filling, melt the chocolate in a heatproof bowl set over a saucepan of gently simmering water, then leave to cool slightly. Place the crème fraîche in a bowl and stir in the melted chocolate. Chill while you make the meringue.
Line a 20 x 30 cm (8 x 12 inch) Swiss roll tin with nonstick baking paper. Whisk the egg whites in a clean large bowl with a hand-held electric whisk until stiff, then gradually whisk in the sugar until the mixture is thick and glossy. Gently fold in the vinegar, cornflour and vanilla extract.
Spread the mixture into the prepared tin and place in the centre of a preheated oven, 180°C (350°F), Gas Mark 4, for 15 minutes. Leave to cool in the tin for 5 minutes.
Turn out the meringue on to another piece of baking paper and spread the chocolate filling evenly over the top. Sprinkle with the raspberries and roll up the meringue.
Transfer to a serving plate and drizzle with the melted white chocolate before serving.