Ingredients :
For the Hazelnut Crust:
1/2 cup (57g) hazelnuts
2 cups (171 g) graham cracker crumbs
1/3 cup (67 g) granulated sugar
1/4 teaspoon of salt
1/2 cup (113 g) melted unsalted butter

For the orange and mascarpone cheesecake:
(4) 8-ounce (906 g) blocks of room temperature full-fat cream cheese
8 ounces (226 g) mascarpone cheese, room temperature
1 and 1/4 cups (249 g) granulated sugar
2 teaspoons of pure vanilla extract
1 and 1/2 tablespoons (18 g) finely grated orange zest
5 large eggs room temperature
3 large egg yolks, room temperature
1/2 cup (113 ml) freshly squeezed orange juice
1/4 cup (57 ml) heavy cream, room temperature
2 teaspoons all-purpose flour

For the chocolate ganache:
7 ounces (226 g) finely chopped 70% dark chocolate
1 cup (227 ml) heavy cream
1 and 1/2 tablespoons Grand Marnier liqueur
candied orange slices for garnish, optional

Instructions :
For the Hazelnut Crust:
Preheat oven to 350 degrees (F). Wrap the bottom and sides of a 9″ springform pan with extra large, heavy-duty foil. I recommend doing several diligent layers here to prevent water from seeping in when you place the pan in the water bath. Lightly spray the pan with nonstick spray, then set aside.
Place the hazelnuts in the body of a food processor and pulse until the nuts are completely ground into fine crumbs.

In a large bowl, combine the hazelnut crumbs, graham cracker crumbs, sugar and salt. Add the melted butter and, using a rubber spatula, mix well to combine. Pour the crust into the prepared pan. Pat the mixture firmly into the prepared pan, working it from the center out to the sides.
Bake for 10 minutes.

Place the crust on a cooling rack while you prepare the filling. Reduce oven temperature to 300 degrees (F).

For the Orange Mascarpone Cheesecake:
Place the cheesecake pan in a large, deep saucepan. Fill the saucepan with 2 1/2 inches of hot water. This is your double boiler and will help ensure your cheesecake comes out without cracks.

Carefully place the mold in the oven and bake for 1h30. Turn off the oven and let the cheesecake sit, undisturbed, for 30 minutes inside the oven with the door closed. The cheesecake should still be slightly wavy.

Remove the cake from the oven and gently run a knife around the edge of the cake. Place the cheesecake on a cooling rack and let it cool completely, then cover the pan lightly with saran wrap and refrigerate for at least 6 hours. Do not remove the pan until it has completely cooled!
For the chocolate ganache:
Chop the chocolate and place it in a heatproof bowl. Put aside.

Pour the cream into a small saucepan and bring to a boil over medium-high heat. Pour the hot cream over the chopped chocolate and let sit for 5 minutes. Then whisk the mixture vigorously until it is smooth and creamy. Whisk the grand marnier. Let the chocolate sit for 10 minutes, then pour over the cooled cheesecake. Leave the chocolate to set for 20 minutes, then decorate with candied orange slices, slice and serve.

Let the chocolate sit for 10 minutes, then pour over the cooled cheesecake. Leave the chocolate to set for 20 minutes, then decorate with candied orange slices, slice and serve.