• Preheat the oven to 170°C/Gas Mark 3.
• Grease a 23cm bundt tin with butter or oil and dust lightly with flour, removing excess.
• Melt the butter and chocolate in a large bowl over a pan of gently simmering water.
• Ensure the water doesn’t touch the bowl’s base.
• Remove from heat once melted.
• In another bowl, whisk the egg yolks with half the sugar until pale and fluffy.
• In a separate clean bowl, whisk the egg whites with the remaining sugar until stiff peaks form.
• Combine the ground almonds and hazelnuts, breaking up any lumps.
• Gently fold the melted chocolate and butter mixture into the egg yolk mixture.
• Using a large metal spoon, fold in the whisked egg whites alternately with the ground nuts until fully combined.
• Transfer the mixture to the prepared tin and bake for 45–50 minutes, or until a skewer inserted in the center comes out clean.
• Cool the cake in the tin for 10 minutes, then turn out onto a wire rack to cool completely.

For the Caramel Hazelnuts:

• Lightly oil a baking tray.
• Heat a deep, heavy-based pan over high heat and add a tablespoon of sugar.
• Stir continuously until the sugar begins to dissolve.
• Gradually add more sugar, one tablespoon at a time, until all the sugar has melted and turned golden caramel.
• Immediately stir in the chopped hazelnuts and pour the mixture onto the oiled tray to cool.
• Once cooled, chop the caramelized hazelnuts into pieces.

For the Ganache:

• Bring the cream to a boil and pour over the chopped chocolate in a bowl.
• Let stand for 1 minute, then whisk until smooth and shiny.
• Drizzle the ganache over the cooled cake, allowing it to set for 10 minutes.

For the Whipped Cream:

• Whisk the double cream with the vanilla extract and icing sugar until firm peaks form.
• Spoon or pipe the whipped cream into the center of the cake.
• Sprinkle the caramelized hazelnuts on top of the whipped cream.

To Decorate:

• If using, apply fragments of gold leaf to the cake using the tip of a small knife.