Combine sugar, cocoa powder, cornstarch, and salt together in a heavy-bottomed saucepan.
⅔ cup sugar, ⅔ cup cocoa powder, ¼ cup cornstarch, ⅛ teaspoon salt
Whisk in milk.
4 cups milk
Heat over medium-low heat. Stir often with the whisk or a spoon to avoid burning.
Heat until the pudding simmers and thickens.
Remove from heat, stir in vanilla and then pour into a large bowl or individual serving dishes.
1½ teaspoons vanilla
Cover with plastic wrap. The plastic wrap should be in direct contact with the pudding in order to prevent a skin from developing on the surface.
Refrigerate until chilled.
Serve with a dollop of whipped cream and fresh berries, if desired.
Notes
Whole milk will produce the richest tasting pudding.
Stir the pudding often. It will easily burn if not stirred.
You may find areas near the bottom of the pan that begin to thicken before the rest of the pudding. Just keep stirring to mix together.
Be certain to cover the pudding with plastic wrap with direct contact to the pudding. This will help prevent a skin from developing on the surface of the pudding.