Instructions

1. For the lemon-hazelnut syrup: in a small saucepan, combine the lemon juice, 1/2 cup water, and the sugar over medium heat. Bring to a boil, reduce the heat, and simmer for 5 minutes, stirring occasionally, until the sugar has dissolved. Take the pan off the heat and allow the syrup to cool, about 20 minutes. Stir in the hazelnut liqueur.

2. For the tiramisu: in a food processor or blender, pulse the hazelnuts until finely chopped (but not a paste). Add the lemon zest and pulse once to combine. Set aside.
3. In the bowl of an electric mixer fitted with the whisk attachment, whip the heavy cream in a large bowl until thick. Add the cinnamon and 2 tablespoons of the sugar and continue to whip until the cream holds soft peaks. In another bowl, beat together the remaining 3 tablespoons sugar and the mascarpone cheese for 30 seconds. Mix one-quarter of the whipped cream into the mascarpone mixture. Using a rubber spatula, fold in the remaining whipped cream. Set aside.
4. Pour the lemon-hazelnut syrup into a small, shallow bowl. Dip 16 of the ladyfinger cookies in the syrup. Line the bottom of a 13 x 9 x 2-inch serving dish or other decorative serving dish with the dipped cookies, trimming the cookies, as necessary, to form an even layer. Spread one-third of the mascarpone mixture over the cookies. Sprinkle with one-third of the hazelnut mixture.
5. Form 2 more identical layers, each consisting of 16 dipped ladyfinger cookies and ending with a layer of the mascarpone mixture sprinkled with the hazelnut mixture. Cover and refrigerate for at least 6 hours or preferably overnight. Remove the tiramisu from the refrigerator at least 1 hour before serving.