01 - In a medium saucepan, whisk together sugar, cocoa powder, cornstarch, and salt until fully incorporated.
02 - Gradually whisk in the whole milk and heavy cream until the mixture is smooth and free of lumps.
03 - Place the saucepan over medium heat and cook while whisking constantly until the mixture thickens and begins to bubble, approximately 6 to 8 minutes.
04 - Remove from heat immediately and stir in the chopped dark chocolate until completely melted and the pudding achieves a smooth texture.
05 - Stir in the vanilla extract until evenly distributed.
06 - Pour the hot pudding into individual serving dishes or ramekins. Cover each surface with plastic wrap to avoid skin formation.
07 - Refrigerate for a minimum of 2 hours until fully chilled and set.
08 - Serve chilled as is, or optionally topped with whipped cream or chocolate shavings.