Combine the 1 ½ cups sugar, cocoa, cornstarch, and salt in a saucepan. Whisk in the milk until the cocoa sugar mixture are well combined and smooth. Using a wooden spoon, cook the mixture and stir over medium-low heat until the mixture boils.

Remove from the heat. Slowly add about 1 cup of chocolate mixture in with the egg mixture stirring constantly. Return the egg mixture into the hot chocolate mixture. Continue to cook until the mixture begins to boil and coats the back of the spoon. Cook an additional 2 minutes. Remove from the heat. Stir in vanilla the 4 cups of heavy cream

Pour the cooked custard mixture through a fine-mesh strainer into a heat-proof bowl. Cover the custard with plastic wrap and refrigerate overnight or at least 8 hours.

Pour the cooked mixture that has been refrigerated OVERNIGHT into the chilled ice cream drum. Put the chilled dasher in place. Place the lid on the metal ice cream container.  Carefully lift the cylinder and place it into the bucket. Attach the motor of the ice cream maker.  Plug the motor into an electric socket and begin churning.

While the motor churning/spinning layer with ice and rock salt. The White Mountain ice cream freezer generally freezes the ice cream in just 15-20 minutes.  The motor will begin to sound slower as the ice cream begins to thicken and freeze  **It’s best to read the directions that come with your particular ice cream maker.  Keep the ice level even with the bottom of the lid by adding more crushed ice and needed along with rock salt.

After about 15-20 minutes you should start to hear your motor slowing down a bit.  This means the ice cream has become thick and the motor is struggling to churn.  At this point, unplug the motor and remove it.  Wipe away any ice and rock salt.  Carefully lift the lid making sure that non of the ice or rock salt falls into your beautifully churned ice cream. Carefully lift the center dasher and scrape off the ice cream that has stuck to the dasher back into the churned ice cream. Clean up the edges of the ice cream by scraping the sides of the cylinder.  Replace the lid.  

After the lid has been corked and placed over the ice cream, cover the lid with more crushed ice and rock salt.  

Wrap the entire ice cream maker with a couple of towel large beach towels or a small blanket.  Let this sit for about an hour or so.  The ice cream will continue to harden up a bit.  This will allow the ice cream to “ripen”.  Carefully unwrap and remove the ice and rock salt from the top.  Lift the cylinder out of the icy/brine solution and serve.