Start by preheating your oven to 375° F. Grease a 9-inch springform pan with non-stick cooking spray and set it aside. Lining the bottom with parchment paper is a great idea for easy removal later.
In a microwave-safe bowl, melt the butter and bittersweet chocolate chips together. Stir every 20 seconds until completely melted and smooth. This creates a rich, luscious base for your crust.
Once melted, remove the bowl from the microwave and add in the granulated sugar, eggs (one at a time), and vanilla extract. Mix until everything is well combined and smooth.
Next, sift in the unsweetened cocoa powder and gently stir in a pinch of salt. This will enrich the chocolate flavor significantly.
Now, fold in the dark chocolate chips just until combined. You don’t want to overmix at this stage.
Pour the cake batter into the prepared pan and bake for 20 to 25 minutes, or until just set. The middle should still be slightly jiggly. Once baked, remove from the oven and allow to cool completely.
While the cake cools, reduce the oven temperature to 325° F. In a small bowl, combine the bittersweet chocolate and dark chocolate chips, and melt them in the microwave the same way.
In a large mixing bowl or stand mixer, blend the cream cheese for about 30 seconds until smooth. Add in granulated sugar, vanilla extract, and sifted unsweetened cocoa powder. Mix until fully incorporated.
Stir in the melted chocolate mixture, espresso, and heavy cream. Mix until you achieve a smooth consistency, scraping down the sides of the bowl to ensure no lumps remain.
In a separate bowl, crack the eggs and beat well. With the mixer on low, slowly add the eggs to the cream cheese mixture until combined. Be careful not to overmix.
Tap the bowl on the counter for about 30 to 45 seconds to release air bubbles. You should see them popping on the surface. This step is crucial for a smooth cheesecake.
Pour the filling over the cooled cake layer in the springform pan. Bake for 30 minutes at 325° F, then reduce the temperature to 250° F and continue cooking for another 45 minutes.
After the baking time, turn off the oven and leave the cheesecake inside for an additional 30 minutes for carryover cooking. This will prevent cracking.
Crack the oven door and let the cheesecake cool slowly for one hour before removing it. Once slightly warm, transfer the cheesecake to the counter to reach room temperature for about 3 to 4 hours.
In the meantime, prepare the mousse layer. Melt the semi-sweet chocolate chips in a microwave-safe bowl, stirring every 20 seconds until smooth. Set aside to cool.
In another bowl, whip the cream cheese until smooth. Add the melted chocolate and mix until well combined. Set this aside.
In a chilled bowl, combine heavy whipping cream, powdered sugar, and vanilla extract, then sift in the cocoa powder. Whip until stiff peaks form. This will add lightness to your mousse.
Gently fold the chocolate whipped cream mixture into the cream cheese mixture in increments, ensuring there are no streaks remaining.
Spread the chocolate mousse over the chilled cheesecake and smooth it out evenly. Cover loosely with plastic wrap and refrigerate for at least 1 and a half hours.
For the ganache, heat the heavy cream until very hot and then add the chocolate chips, letting them sit for 5 minutes before stirring until smooth.
Pour the ganache over the chilled cheesecake, allowing it to drip over the edges naturally. If needed, smooth it out with an offset spatula.
Return the cheesecake to the refrigerator uncovered while you prepare the chocolate shavings for decoration. Use a knife or vegetable peeler to create chocolate curls from the dark chocolate bar.
Serve immediately or cover and refrigerate until you’re ready to enjoy this rich Dark Chocolate Cheesecake. Pair with homemade whipped cream if desired!
