Microwave the chopped chocolate and heavy cream in a microwave-safe bowl on 50% power for 90 seconds. Stir until melted and smooth, then set aside to cool.
In a stand mixer fitted with the paddle attachment, beat the cream cheese until smooth, about 1-2 minutes. Scrape down the sides as needed.
Add the sugar and mix until fully combined. Next, beat in the cocoa powder, scraping down the bowl to ensure even mixing.
Add the eggs, one at a time, beating just until incorporated between each. Finally, mix in the melted chocolate and cream, taking care not to overbeat.
Tip: Overbeating can cause cracks by incorporating too much air, leading to a spongy texture. Use room-temperature ingredients and mix slowly to achieve a smooth, dense batter.
Pour the batter into the prepared crust. Place the springform pan on a baking sheet and bake for about 50 minutes, until the top looks slightly puffy and dry, with a slightly wobbly center.
Turn off the oven, crack the door open, and allow the cheesecake to cool for 10 minutes inside the oven. This helps prevent cracking. Then, transfer it to a wire rack to cool completely.
Refrigerate for at least 4 hours, or overnight, until fully chilled.
Before serving, release the cheesecake from the pan and garnish with spooky meringue ghosts.