Preheat the oven to 325°F (160°C). Grease a springform pan lightly.
In a mixing bowl, combine the crushed graham crackers, melted butter, and sugar. Mix until well combined.
Press the graham cracker mixture firmly into the bottom of the prepared pan to form a crust. Bake for 10 minutes, then remove from the oven and let it cool slightly.
In a large mixing bowl, beat the softened cream cheese until smooth and creamy.
Gradually add the sweetened condensed milk, heavy cream, cocoa powder, and vanilla extract. Continue mixing until all ingredients are well incorporated.
Pour the filling over the cooled graham cracker crust. Smooth the top with a spatula.
Bake the cheesecake for 50-60 minutes, or until the edges are set but the center has a slight jiggle.
Remove from the oven and let it cool at room temperature before transferring to the refrigerator. Chill for at least 4 hours, ideally overnight.
Before serving, garnish with chocolate sauce, chocolate shavings, or mini brigadeiros if desired.