Inspired by the Torta Setteveil but simplified to four layers, this hazelnut sponge is layered with smooth chocolate mousse, soft mascarpone, and topped with nuts for added texture...
Making the hazelnut sponge Preheat the oven to 160ºC. Grease a 20 cm springform tin and line with parchment paper. Fit the K-Beater. Add butter and sugar into the Appliance bowl. Mix for 2 minutes on speed 2, until combined and then scrape the bowl. Add eggs when the machine is running. Mix for 2 minutes on speed 1, until combined. Add vanilla extract, buttermilk and olive oil. Mix for 30 seconds on speed Min, and then scrape the bowl. Add flour, baking powder and hazelnuts. Mix for 1 minute on speed Min. Transfer the batter into the tin. Bake for 1 hour at 160ºC, until a skewer inserted comes out clean. Remove from the oven and let cool in the tin for 20 minutes. Then remove from the tin and let cool completely.
Clean the springform tin, grease, line the bottom with parchment paper and sides with acetate. Place the hazelnut sponge in the base of the lined tin and set aside.
Making the dark chocolate mousse Add melted chocolate and egg yolks into a clean bowl. Mix until combined and set aside. Tip: Work quickly as the chocolate will start to set. Clean the Appliance bowl and fit the Whisk Tool. Add egg whites into the Appliance bowl. Mix for 1 minute on speed Max. Add sugar gradually when the machine is running. Mix for 3 minutes on speed Max, until stiff peaks form. Transfer the mixture into a clean bowl. Add cream into the Appliance bowl. Tip: No need to clean the bowl or the Whisk Tool. Mix for 1 minute 20 seconds on speed Max, until soft peaks form. Carefully fold one third of meringue and one third of whipped cream to the chocolate mixture until combined. Repeat the same process with the remaining mixtures. Spread the sponge with the chocolate mousse evenly. Chill for 3 hours in the fridge, until set. Tip: For best results, chill overnight.
Making the cream topping Clean the Appliance bowl and fit the Whisk Tool. Add cream and mascarpone into the Appliance bowl. Mix for 1 minute, speed Max until soft peaks form. Transfer the mixture into the tin and spread evenly on the chocolate mousse. Make small peaks using a spatula or back of a spoon. Chill in the fridge until needed.
Making the frosted nuts Line a baking tray with parchment paper. Add hazelnuts, pecans, sugar and water into a saucepan and mix until combined. Heat for 10 minutes on a medium heat, stirring constantly, until the sugar crystallises. Transfer the mixture into the baking tray and let cool completely.
Remove the cake from the tin and remove the acetate and parchment paper. Place the cake on a serving plate. Break the frosted nuts apart and scatter over the cake.
Serve.
Substitutions Whipping cream can be replaced with double cream.