Preheat oven to 325 degrees F. In a medium saucepan, combine milk, sugar, cocoa powder, and coffee crystals. Cook and stir just until cocoa and coffee are dissolved.
In a medium mixing bowl, gradually whisk hot mixture into eggs. Add vanilla. Place six 6-ounce custard cups in a 3-quart rectangular baking dish. Place on the oven rack. Pour egg mixture into the custard cups. Carefully pour boiling water around the custard cups into the baking dish to a depth of about 1 inch.
Bake for 30 to 35 minutes or until a knife inserted near the center comes out clean. Remove the custard cups from baking dish. Cool to room temperature. Chill in the refrigerator 2 to 24 hours. If desired, top with dessert topping and coffee beans.