To make the candied walnuts, place the sugar, maple syrup and water in a pan over a medium heat until the sugar has dissolved and it begins to boil. Place the walnut halves in a bowl and pour over the syrup, stirring for a minute and leaving to steep for three. Place a sheet of baking parchment on a baking sheet and top with a wire rack then carefully scoop each walnut out of the bowl and place on the rack. Allow the syrup to drip off the walnuts as you preheat the oven to 170oc/150oc fan. Once drip dried, place on a baking sheet lined with fresh parchment and bake for 15 minutes, stirring the walnuts every five minutes until golden. Remove from the oven and leave to cool. Pick around ten to 12 walnut halves and spray with edible silver paint before leaving to dry.
To make the cake, grease and line three 18cm sandwich tins with baking parchment and preheat the oven to 180oc/160oc. Place the chocolate in a heatproof bowl over a pan of barely simmering water and slowly melt before removing from the heat and leaving to cool slightly. Meanwhile, whisk the boiling water and cocoa powder together in a separate bowl and add the buttermilk. In another bowl, whisk together the flour, bicarbonate of soda and salt and set aside.
In the bowl of a stand mixer fitting with the paddle attachment, beat the butter and sugar together for around five minutes. It will clump together like dough but persevere; it will go smooth as the butter melts slightly. Add the vanilla and a third of the eggs then beat again, adding the remaining eggs until the batter is smooth and a nice caramel colour. Scrape down the sides of the bowl and beat again briefly then turn the mixer to low and pour in the melted chocolate. Once mixed and the sides scraped, add half the buttermilk and a third of the dry mix and beat on low. Repeat again then fold in the last of the flour, ensuring the batter is smooth and the ingredients are well mixed. Divide between the three tins and bake for 25 to 30 minutes until a skewer inserted in the middle comes out clean. Remove from the oven and cool in the tins for 10 minutes before turning out and removing the parchment paper, leaving to cool completely.
To make the maple Swiss meringue buttercream, place the egg whites, sugar and salt in the bowl of a stand mixer and place over a pan of barely simmering water, ensuring the bowl doesn’t touch the water. Stir using a whisk until the sugar has completely dissolved – you can tell by rubbing the mix between your fingers without feeling any sugar grains. If you want to pasteruise the mix, carefully heat to 70oc using a sugar thermometer or simply remove from the heat once the sugar has dissolved and place back in the stand mixer with the whisk attachment. Whisk on high until stiff peaks are formed and the bowl has cooled to room temperature. Add the butter piece by piece with the mixer still running until the meringue is a buttery yellow. Add the maple syrup and whisk to incorporate, then you are ready to put the cake together.
To assemble, place one of the cakes on a cake stand and smooth over a third of the buttercream. Sprinkle over half the chopped candied walnuts then top with the second cake and repeat again. Place the final cake on top, upside down to create a flat top and spread over the remaining buttercream, finishing with a swirl by pressing down with a palate knife at an angle and spinning your wrist round in a quick motion. Press the silver walnut halves around the cake standing upwards and scatter any remaining walnut pieces in between. Add long spindly candles and serve.
Recipe by Victoria Sponge Pease Pudding at http://victoriaspongepeasepudding.com/baking/maple-and-candied-walnut-chocolate-celebration-cake/