Chocolate meringue Mont Blanc cake - Good Food Middle East

Ingredients

• 300g butter, plus extra for greasing
• 200g dark chocolate, finely chopped
• 2 large eggs, plus 3 yolks
• 200g golden caster sugar
• 140g light brown soft sugar
• 200g chestnut purée from a 415g can (reserve the rest for the filling, below)
• 175g plain flour
• 50g cocoa powder
• 1½ tsp baking powder
• 3 large egg whites
• 140g golden caster sugar
• 300ml pot double cream
• 215g chestnut purée (from can, above)
• 100g icing sugar, plus extra for dusting
• chocolate shavings (optional)