Preheat the oven to 325°F (163°C). Grease the springform pan and line the bottom with parchment paper.
In a mixing bowl, combine graham cracker crumbs, cocoa powder, sugar, and melted butter. Mix until well combined.
Press the crumb mixture into the bottom of the prepared springform pan to form a crust. Bake for 10 minutes, then remove and let cool.
In another mixing bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth and creamy.
Gradually add granulated sugar and vanilla extract, mixing until well blended.
Add the eggs, one at a time, mixing on low speed until just incorporated after each addition. Avoid overmixing.
Stir in the melted chocolate until fully combined.
Pour the cream cheese mixture over the cooled crust in the springform pan, smoothing the top with a spatula.
Bake the cheesecake in the preheated oven for about 50 to 60 minutes, or until the center is set but slightly jiggles when shaken.
Remove from the oven and allow it to cool for 10 minutes. Run a knife around the edges to loosen, then let it cool completely at room temperature.
Once cooled, refrigerate the cheesecake for at least 4 hours or overnight.
Before serving, top with assorted colorful candies, pressing them gently into the surface.