Preheat the oven to 350F.
In a large bowl, whisk the sugar, cocoa powder, evaporated milk, butter, eggs, and vanilla until smooth. Pour into the prepared pie crust.
Bake for 45 minutes or until the edges are set and the center of the pie is still slightly jiggly. Place the pie plate on a rack to cool slightly before serving.
May be served hot, cold, or at room temperature. Enjoy!
Adapted from Handle the Heat