In a medium sauce pan, bring 2 cups of milk to a boil over medium low heat.
While the milk is heating, in a separate bowl, combine the sugar, cornstarch, and salt then stir in the remaining 1/2 cup of milk and 2 egg yolks. Whisk until well combined.
Gradually add half of the hot milk, whisking constantly, to the egg yolk mixture.
Return milk mixture to the pan and stir constantly over medium heat for 2 to 4 minutes as the mixture thickens into pudding consistency and begins to boil.
Remove from heat and stir in butter, vanilla, and dark chocolate.
Notes
To serve warm, cool just slightly, top with raspberries and enjoy immediately.
To serve cold, spoon pudding into a bowl. Place bowl in a large ice-filled bowl for 15 minutes or until pudding is cool. Cover surface of pudding with plastic wrap and chill until ready to serve.