Preheat your oven to 350°F (175°C).

In a medium bowl, mix graham cracker crumbs with melted unsalted butter until resembling wet sand. Firmly press into the bottom of a springform pan to create an even crust. Bake for 10 minutes, then allow to cool completely.

In a large mixing bowl, beat cream cheese until smooth, about 2 minutes. Gradually add granulated sugar and mix well. Gently blend in orange zest and juice until creamy.

Chop the dark chocolate and melt in the microwave in 30-second intervals. Allow it to cool slightly before folding into the cream cheese mixture.

In a separate bowl, whip heavy cream until soft peaks form. Gradually fold it into the chocolate cream cheese mixture.

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

Melt additional dark chocolate to drizzle over the top. Garnish with fresh orange slices before serving.