Make the Flourless Cake Base: Start by melting the butter and chocolate together. Use a microwave in 10-second intervals, stirring frequently to avoid scorching. Once smooth, let it cool slightly. In a bowl, whisk together the eggs, cocoa powder, and sugar. Gradually fold in the melted chocolate mixture. Line your springform pan with parchment paper, spray it with non-stick spray, and pour in the batter. Set it aside while preparing the cheesecake layer.

Prepare the Cheesecake Layer: Using an electric mixer, beat the softened cream cheese until light and fluffy. Add the sugar and mix well. Incorporate the eggs one at a time, then add vanilla extract. Slowly pour in the melted chocolate and mix until smooth. Pour this cheesecake batter over the unbaked flourless cake base. Smooth the top with a spatula.

Bake the Cheesecake: Preheat your oven to 350°F (175°C). Bake the layered cheesecake for 50-60 minutes or until the center is slightly set. Turn off the oven and let the cheesecake cool inside with the door ajar to prevent cracks. Once cooled to room temperature, refrigerate for at least 2 hours.

Whip Up the Chocolate Mousse: Whisk the heavy cream until stiff peaks be careful not to overwhip, as it can turn into butter. Fold in the melted and cooled chocolate until fully combined. Spread this mousse over the chilled cheesecake layer, smoothing it out evenly.

Add the Ganache Glaze: Melt the chocolate chips, butter, and corn syrup together in the microwave, stirring every 10 seconds until smooth. Let the ganache cool slightly before pouring it over the mousse layer. Spread gently to create a glossy finish. Refrigerate the cheesecake for another 1-2 hours until set.