Method

• 1.
  For coffee syrup, combine all ingredients in a medium bowl and whisk until sugar and coffee are completely dissolved. Set aside to cool until ready to assemble.
• 2.
  In a stand mixer fitted with the whisk attachment, whisk mascarpone and hazelnut cream on low speed until fully combined. In a separate bowl, whisk cream until soft peaks form. Add cream to mascarpone mixture, whisking at high speed for a few seconds until soft peaks form. Be careful not to over-whip. Transfer to a large bowl, cover with plastic wrap and refrigerate to rest.
• 3.
  Meanwhile, in a clean bowl of a stand mixer fitted with the whisk attachment, whisk yolks on high until fluffy and doubled in volume. Combine sugar and 2 tbs water in a small saucepan. Bring to boil and cook until syrup reaches 121°C on a sugar thermometer. Squeeze out excess water from gelatine and add to hot syrup, stirring to dissolve. Slowly pour hot mixture into the whipped yolks, mixing slowly at first. Once syrup is incorporated, keep whisking at maximum speed for 10 minutes, or until thick and glossy.
• 4.
  Gently fold the egg mixture into the mascarpone mixture using a plastic spatula – be careful not to overmix. Spoon 1 cup of mixture into a piping bag (or zip-lock bag) and refrigerate until ready to serve.
• 5.
  To assemble, working with a few biscuits at a time, dip savoiardi into coffee syrup for about 4 seconds, making sure they are soaked but not soggy, then arrange in a single layer at the bottom of a 25cm square, 7cm-deep dish. Repeat to form a second layer of biscuits. Spread over the hazelnut mascarpone mixture, using a spatula or the back of a spoon to smooth it out. Cover with plastic wrap and refrigerate for at least 3-4 hours, or preferably overnight, to allow flavours to meld and tiramisu to set.
• 6.
  To serve, cut tiramisu into squares and lift portions using an egg flip into plate (see notes). Sprinkle with cocoa. Cut a small opening from the bag of reserved hazelnut-mascarpone mixture and pipe over each portion in a zigzag fashion, draping slightly over the sides. Sprinkle with a little roasted hazelnut and, using a microplane, finely grate some hazelnut over to finish.