Preheat the oven to 325°F (163°C).

Prepare the crust by mixing graham cracker crumbs, cocoa powder, and melted butter.

Press the crust mixture into the bottom of a springform pan and bake for 10 minutes.

In a large bowl, beat the cream cheese and sugar until smooth and creamy.

Add the melted dark chocolate, eggs, sour cream, and vanilla extract to the creamy mixture.

Blend the mixture until completely smooth and creamy, then gently fold in the fresh raspberries.

Pour the cheesecake filling over the pre-baked crust, spreading it evenly.

Bake in the preheated oven for 50-60 minutes or until the edges are set and the center is slightly jiggly.

Allow the cheesecake to cool completely, then refrigerate for at least 4 hours before serving.

Once set, carefully remove the sides of the springform pan and garnish with fresh raspberries or chocolate shavings if desired.