Method

• 1.
  To make the Nutella ganache, place Nutella, cocoa and 100ml cream in a bowl and stir to combine.
• 2.
  To make the mascarpone cream, place egg yolks and sugar in a stand mixer fitted with the whisk attachment and whisk for 4-5 minutes or until thick and pale. Add mascarpone and remaining 150ml cream, and whisk until thick and combined. Transfer to a bowl and set aside.
• 3.
  Clean stand mixer bowl and whisk, and dry well. Add eggwhites and whisk to stiff peaks. In 2 batches, gently fold eggwhite into the mascarpone mixture, then chill for 1 hour or until set.
• 4.
  To assemble the tiramisu, combine coffee and hazelnut liqueur in a shallow dish. Dip enough biscuits into the coffee mixture to cover the base of a 2L (8-cup) dish. Cover biscuits with half the hazelnuts, then spoon over half the Nutella ganache, using a palette knife to spread evenly. Top with half the mascarpone cream and spread evenly. Repeat with remaining biscuits, hazelnuts and Nutella ganache.
• 5.
  For the piped top layer, transfer remaining mascarpone cream to a piping bag fitted with a 1.6cm plain nozzle. Pipe 2cm rounds over tiramisu. Chill for 2 hours or overnight to set slightly. Dust with extra cocoa to serve.