Creating the Chocolate Blueberry Cheesecake is easy if you follow these steps:

1. Preheat the Oven: Preheat your oven to 325°F (160°C).
2. Make the Crust: In a medium bowl, mix chocolate graham cracker crumbs, melted butter, and sugar until well combined. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 10 minutes and then let it cool.
3. Prepare the Filling: In a large mixing bowl, beat the softened cream cheese until smooth. Gradually add the sugar and beat until fluffy. Stir in the vanilla extract.
4. Add Eggs: Add the eggs one at a time, mixing well after each addition. Do not overmix.
5. Incorporate Sour Cream & Cocoa: Blend in sour cream and cocoa powder until the mixture is smooth and well combined.
6. Pour Filling Into Crust: Pour the cheesecake filling over the cooled crust, spreading it evenly with a spatula.
7. Bake: Bake in the preheated oven for 50-60 minutes. The center should be set but slightly jiggly.
8. Cool in Oven: Turn off the oven and crack the door open. Let the cheesecake cool inside the oven for about an hour. This helps prevent cracking.
9. Chill: After cooling, place the cheesecake in the refrigerator for at least 4 hours, or overnight for the best flavor and texture.
10. Prepare Blueberry Topping: In a medium saucepan, combine blueberries, sugar, lemon juice, cornstarch, and water. Cook over medium heat until the mixture thickens and the blueberries burst (about 5-7 minutes). Remove from heat and let cool.
11. Top the Cheesecake: Once the cheesecake is set, spread the blueberry mixture evenly over the top, allowing it to cascade down the sides for visual appeal.

With these straightforward steps, your Chocolate Blueberry Cheesecake will be ready to impress!