Preheat oven to 325°F (163°C).
Mix chocolate cookie crumbs and melted butter. Press into a springform pan.
Bake crust for 8–10 minutes and cool slightly.
Beat cream cheese until smooth. Add sugar, sour cream, and vanilla.
Add eggs one at a time, mixing gently. Stir in melted chocolate.
Pour filling over crust.
Bake 55–65 minutes until edges are set and center slightly jiggles.
Turn off oven and crack door slightly. Cool gradually.
Refrigerate cheesecake at least 4 hours or overnight.
For topping, combine evaporated milk, brown sugar, butter, egg yolks, and vanilla in a saucepan.
Cook over medium heat until thickened, stirring constantly.
Remove from heat and stir in coconut and pecans. Cool slightly.
Spread topping over chilled cheesecake.
Garnish with chocolate drizzle or whipped cream if desired.
Slice and serve chilled.