Method

• 1.
  Preheat oven to 180°C. Grease a 25cm springform pan and line with baking paper.
• 2.
  Prepare brownie mix according to packet instructions and pour into prepared pan. Bake, removing 5 minutes before suggested total cooking time so it is slightly undercooked. Remove from oven and cool completely, then remove from pan. Set aside until needed.
• 3.
  Grease side of the 25cm springform cake pan. Line base with baking paper and double line side, allowing 3cm above the pan, with sheets of acetate. Place the cooled brownie in base of prepared pan. Set aside.
• 4.
  For the vanilla panna cotta, place cream, sugar and vanilla in a saucepan over medium heat. Bring to barely a simmer, stirring regularly. Remove from the heat. Squeeze excess water from gelatine, then stir into the cream mixture until melted and combined. Strain the mixture through a fine sieve into a bowl, then cover surface directly with plastic wrap and chill for at least 1 hour 30 minutes to firm (to speed up the process, place the bowl over another bowl half filled with ice). Transfer the panna cotta filling to the bowl of a stand mixer fitted with the whisk attachment. Whisk for 1 minute or until smooth and soft peaks form, being careful not to over whisk. Spoon over brownie base, ensuring the panna cotta reaches the edges. Smooth with a palette knife and chill in the fridge for 2-3 hours until set.

• 5.
  For the mousse, combine 300ml cream, sugar and cocoa powder with 300ml water in a saucepan over medium heat. Bring to a simmer, whisking constantly. Add chocolate and bring back to barely a simmer, stirring constantly. Squeeze excess water from gelatine, then stir into the chocolate mixture until melted and combined. Pour mixture through a fine sieve into a large bowl, then cover surface directly with plastic wrap and chill for at least 1 hour 30 minutes to firm (to speed up the process, place the bowl over another bowl half filled with ice).
• 6.
  Place remaining 475ml cream in the bowl of a stand mixer with the whisk attachment, and whisk to medium peaks. Transfer to a clean bowl.
• 7.
  Place chilled chocolate cream mixture in the clean bowl of a stand mixer with the whisk attachment and whisk to loosen for 30 seconds. Gently fold in whipped cream in 2 batches. Spoon mousse mixture over the panna cotta layer, ensuring it reaches the edges. Smooth over top with a palette knife. Place in freezer for 2-3 hours or, if time permits, overnight.
• 8.
  For the glaze, place chocolate in a heatproof bowl. Combine cream and glucose syrup in a small saucepan over medium-low heat and bring to a simmer, stirring regularly. Pour hot cream mixture over chocolate, stand undisturbed for 3 minutes, then whisk until fully combined and smooth. Allow to cool to room temperature (the glaze needs to be a pourable consistency, but not warm).
• 9.
  Remove cake from pan and carefully peel away acetate. Place cake on a slightly smaller cake pan set over a large tray and generously pour over the glaze, taking care to ensure there are no bare spots. Allow the excess glaze to drip off for 5 minutes. Scape the bottom edges to remove any remaining drops and carefully transfer to a serving platter or cake stand. Allow to defrost in fridge for 3 hours or overnight. Sit at room temperature for 20 minutes before serving. Sprinkle with edible gold dust and top with chocolate shards and edible gold leaf, if using, to serve.