Preheat the oven to 180°C/gas 4.
Take a large swiss roll tin and line with foil building up the sides to make a frame about 3-4 cm high. Scrunch the corners together. Brush the foil with a little vegetable oil.
Make the meringue
Separate the egg whites carefully from the yolks and in a clean mixing bowl whisk the egg whites until they form stiff peaks. Mix in the vinegar and then fold in the corn flour.
Gradually add the sugar and whisk quickly for 4-5 minutes until stiff peaks form.
Using a palette knife smooth the meringue into the prepared tin and spread evenly. Cook in the oven for 25-30 minutes or until starting to faintly brown and firm to the touch.
Allow to cool for 5 minutes then turn out upside down onto a sheet of foil (larger than the area of the meringue) and remove the cooking foil used for cooking. Allow to cool completely.
Meanwhile make the filling
Finely grate the white chocolate and place into a mixing bowl. Beat the mascarpone cheese and chocolate together. Whisk the cream and caster sugar together until it starts to thicken, don't over whisk. Fold the cream into the mascarpone and blend together until smooth.
Assemble the roulade
Spread the cream/chocolate/mascarpone mixture evenly across the meringue leaving a 2cm space along the long sides. Wash and dry and then press the raspberries deeply and evenly into the surface of the cream until they are all used.
Take the foil on one of the longest sides of the roulade and curl it up to lift the edge of the roulade, and then proceed to very gently roll the roulade up and away from you. Make sure you don't roll the foil into the roulade.
Wrap the roulade in the foil and then chill in the fridge for 2 hours. Remove from the fridge and unwrap and place on a serving plate, dust with icing sugar and serve.