1. Prepare the chocolate crust by crushing chocolate graham crackers or Oreos and mixing with melted butter.
2. Press the crust mixture into the bottom of a springform pan and chill in the refrigerator.
3. Preheat the oven to the required temperature.
4. Melt German chocolate and semi-sweet chocolate together, then let it cool slightly.
5. In a large bowl, beat cream cheese and sugar until smooth.
6. Add eggs one at a time, mixing well after each addition.
7. Stir in the melted chocolate, cocoa powder, and sour cream until fully combined.
8. Pour the cheesecake filling over the prepared crust in the springform pan.
9. Wrap the pan with aluminum foil and place it in a larger baking dish filled with hot water for a water bath.
10. Bake the cheesecake until the center is set but slightly jiggly.
11. Turn off the oven, crack the door slightly, and allow the cheesecake to cool inside for about an hour.
12. Remove the cheesecake from the oven and let it cool to room temperature.
13. Refrigerate the cheesecake for at least 4 hours or overnight for best results.
14. Prepare the coconut pecan topping by heating evaporated milk, egg yolks, butter, and sugar in a saucepan.
15. Cook the mixture over medium heat until thickened.
16. Remove from heat, then stir in vanilla, shredded coconut, and chopped pecans.
17. Let the topping cool before spreading it over the chilled cheesecake.
18. Optionally, decorate with chocolate ganache swirls or extra chocolate pieces.
19. Slice and serve the German Chocolate Cheesecake chilled.