Brush 2 x 20 cm (8 inch) round cake tins lightly with oil and line the bases with nonstick baking paper.
Whisk the egg whites in a large, grease-free bowl with a hand-held electric whisk until they form stiff peaks. Gradually whisk in the sugar until thick and glossy. Gently fold in the vinegar, vanilla extract, cornflour and hazelnuts.
Divide the mixture between the prepared tins and bake in a preheated oven, 180°C (350°F), Gas Mark 4 for 30 minutes.
Leave to cool in the tins for 10 minutes, then turn out carefully on to a wire rack and peel off the paper.
Whip the cream in a bowl until it forms soft peaks. Spread over the base of 1 meringue and top with the raspberries, then sandwich together with the remaining meringue. Drizzle over the melted chocolate and chill until ready to serve.