Prue Leith's Prinzregententorte recipe - The Great British Bake Off

Ingredients

• 10 large eggs, separated
• ¼ tsp salt
• 180g caster sugar
• 3 x 8g packets of vanilla sugar
• 175g plain flour
• 1 tsp bicarbonate of soda
• 65g unsalted butter, melted
• 600ml whole milk
• 3 large egg yolks
• 60g cornflour
• 40g cocoa powder
• 150g 54% dark chocolate, chopped
• 375g unsalted butter, softened
• 200g icing sugar, sifted
• edible gold powder
• 200g 54% dark chocolate, chopped
• 300ml double cream
• 25g unsalted butter, softened