Prue Leith's Coffee Walnut Whirls recipe - The Great British Bake Off

Ingredients

• 60g walnuts
• 80g plain flour, plus extra for dusting
• ⅛ tsp baking powder
• 55g unsalted butter
• 40g icing sugar
• 1 egg yolk
• 150ml double cream
• 50g coffee beans
• 250g milk chocolate, chopped
• 2 gelatine leaves
• 2 egg whites
• ½ tsp cream of tartar
• 75g caster sugar
• 125g corn syrup
• 1½ tsp vanilla paste
• 300g 54% dark chocolate
• 8 walnut halves