Grease a 9 inch springform pan and line the bottom with parchment paper.
Chop the chocolate into small pieces. Place in the top pan of a double boiler over simmering water, stirring until the chocolate is fully melted and smooth. Set aside to cool to room temperature. Be sure no moisture or water gets into the melted chocolate.TIP - It’s important to cool down the melted chocolate before adding it to the cheesecake mixture so that it doesn’t melt the other ingredients or ruin the texture of the filling.
Combine chocolate graham cracker crumbs and granulated sugar in a mixing bowl or directly in the bottom of a springform pan. Stir to combine evenly.
Pour the melted butter into the graham cracker crumb mixture and stir to make a sandy mixture. Press the crust across the bottom and up the sides of the springform pan. Place crust in the refrigerator to firm up while preparing the cheesecake.
In a large mixing bowl, beat together cream cheese and sour cream with a mixer until fluffy and smooth.
Add the powdered sugar, beating until combined. Beat in the vanilla extract.
When the chocolate is at room temperature, pour it into the cream cheese mixture and beat to combine.
Add the heavy cream to the cheesecake mixture, beating for 1-2 minutes longer until fluffy and well combined. The cheesecake mixture should form soft peaks.TIP - You can also whip the heavy cream separately and fold it into the cheesecake mixture, but beating it directly into the filling requires less dishes, is simple, and creates a silky, luxurious texture to the cheesecake.
Spread the cheesecake filling evenly into the chilled crust. Use an offset spatula to smooth the top of the cheesecake.
Place cheesecake in the refrigerator for at least 4 hours.
Garnish with fresh raspberries or whipped cream. You can also drizzle with chocolate ganache.
Notes
The cream cheese should be at room temperature so that it mixes smoothly into the cheesecake filling mixture. To help it come to room temp faster, cut the cream cheese into cubes and allow it to rest on the counter for around 30 minutes.
This makes a nice thick crust and full cheesecake. You can easily slice 20 servings.
If desired, you can substitute the chocolate graham crust with a traditional graham cracker crust or an Oreo cookie crust.
A mixture of semi-sweet and bittersweet chocolate keeps this cheesecake rich and decadent without being cloyingly sweet. Use a quality bar of baking chocolate such as Ghiradelli, Lindt, or even Baker's.
Cover leftover cheesecake with plastic wrap or store in an airtight container in the refrigerator for 2-3 days.
To Freeze - Be sure to chill the cheesecake first, then wrap it well with plastic wrap followed by a layer of aluminum foil and freeze for up to 1 month. Freeze overnight in the refrigerator.