Method

• 1.
  Preheat oven to 150°C/130°C fan-forced. Line 3 baking trays with baking paper. Trace an 18cm circle on each piece of paper and flip paper over.
• 2.
  Beat egg whites with a pinch of fine salt in a stand mixer fitted with the whisk attachment on medium-high speed until frothy. Start adding the caster sugar, gradually, as you keep whisking, until glossy, firm peaks form and sugar has dissolved when you rub a little between your fingers. Add vinegar and cornflour, and whisk briefly until combined.
• 3.
  Combine coffee and cocoa in a small bowl, then fold two-thirds through the meringue to create a light swirl effect.
• 4.
  Divide mixture evenly among the prepared trays at centre of each traced circle, forming 3 discs. Sprinkle over the remaining coffee mixture. Reduce oven temperature to 140°C/120°C fan-forced. Bake for 60-75 minutes until crisp and dry, but not coloured. Leave to cool in the oven, with the door ajar, for 2-3 hours.
• 5.
  Beat mascarpone, cream and icing sugar together in a stand mixer fitted with the whisk attachment on medium-high speed until soft peaks form. Fold through three-quarters of the chocolate.
• 6.
  Place one meringue disc on a large serving platter or cake stand. Gently spread over one-third of mascarpone mixture, then repeat with remaining meringue discs and mascarpone mixture. Sprinkle with remaining chocolate to serve.