Preheat your oven to 350°F (175°C). In a mixing bowl, combine the graham cracker crumbs with melted unsalted butter until it resembles wet sand. Press into the bottom of a springform pan. Bake for 10 minutes and let cool.

In a large bowl, beat the cream cheese until smooth. Gradually add granulated sugar, mixing on low speed. Add the orange zest and juice, mixing until well combined.

Melt the dark chocolate until smooth and cool slightly. Fold it into the cream cheese mixture. Whip the heavy cream until stiff peaks form and gently fold into the chocolate mixture.

Pour the filling into the cooled crust, smoothing the top. Cover and refrigerate for at least 4 hours, preferably overnight.

Once chilled, remove the cheesecake from the springform pan. Garnish with melted chocolate and fresh orange slices. Slice and serve.