Step 1
Preheat oven to 180°C. Place the chocolate melts in a small heatproof bowl. Pour over the coffee. Microwave on high, stirring every 30 secs, until the chocolate melts and mixture is smooth and well combined.
Step 2
Line 3 baking trays with baking paper. Draw a 20cm circle on each tray and turn paper over. Use an electric mixer to whisk egg whites in a clean, dry bowl until soft peaks form. Gradually add the sugar, 1 tbs at a time, whisking well after each addition, until sugar completely dissolves and mixture is thick and glossy. Add the cornflour and vinegar and whisk until combined.
Step 3
Divide the meringue mixture into 3 even portions. Spoon onto circles on the lined trays. Spoon 1 tbs of the chocolate mixture over each portion on the lined trays. Using each circle as a guide, gently marble and spread to a 20cm disc. Reduce oven to 120°C. Bake the meringues, swapping trays halfway through cooking, for 1 hour or until dry to touch. Turn oven off. Leave in oven, with door ajar, for 1 hour to cool completely.
Step 4
Use an electric mixer to whisk mascarpone, cream and extra coffee in a bowl until soft peaks form.
Step 5
Place 1 meringue disc on a serving plate. Spoon over one-third of the cream mixture. Continue layering with remaining meringue discs and cream mixture, finishing with cream mixture. Top with raspberries and drizzle with the remaining chocolate mixture. Sprinkle with chocolate curls. Serve immediately.