Preheat oven to 325°F. Mix cookie crumbs, sugar, and melted butter. Press into pan and bake for 10 minutes. Let cool.
Beat cream cheese and sugar until smooth. Mix in cocoa, sour cream, eggs (one at a time), vanilla, and melted chocolate.
Pour filling over crust. Bake 55–65 minutes until just set. Turn off oven, crack door, and cool for 1 hour. Chill at least 4 hours or overnight.
Whisk evaporated milk, brown sugar, and yolks in a saucepan over medium heat. Stir 8–10 minutes until thick. Add butter, vanilla, coconut, and pecans. Cool.
Spread topping over chilled cheesecake. Slice with a warm, clean knife.