Preheat oven to 325°F (163°C). Grease or line a 9-inch springform pan.

1. Crush graham crackers or biscuits into fine crumbs, mix with melted butter, and press firmly into the bottom of the pan to form the crust.
2. In a large bowl, beat cream cheese and sugar until smooth and creamy.
3. Add eggs one at a time, mixing well after each addition. Stir in vanilla extract and sour cream or heavy cream.
4. Pour the filling over the crust and smooth the top.
5. Bake for 50–60 minutes, until edges are set and the center is slightly jiggly.
6. Turn off oven, crack the door, and let cheesecake cool inside for 1 hour.
7. Refrigerate for at least 4 hours or overnight before serving.
8. To make the chocolate sauce, heat heavy cream until simmering, then pour over chopped chocolate. Let sit for 1 minute, then stir until smooth and glossy.
9. Slice cheesecake, drizzle with chocolate sauce, and serve with a scoop of ice cream.