Step 1

In a medium saucepan whisk together 1/2 cup sugar, the cocoa powder, cornstarch and salt.

Step 2

Pour in milk and egg yolks and whisk well.

Step 3

Cook mixture over medium-high heat, stirring constantly and while scraping bottom and sides of pan with a rubber spatula to prevent skin from forming.

Step 4

Once mixture thickens slightly and comes to a simmer (with bubbling across top surface as well not just edges), reduce heat to medium-low, immediately switch to a whisk and let simmer 30 seconds while whisking constantly.

Step 5

Remove from heat and immediately strain mixture through a fine mesh strainer into a heat proof bowl. Right away add chocolate, butter and vanilla while mixture is still very hot and whisk until smooth.

Step 6

Cover mixture with a sheet of plastic wrap while pressing directly against the surface of pudding to prevent a skin from forming.

Step 7

Chill 4 hours.

Step 8

Add heavy cream and 1 Tbsp sugar to a medium bowl and whip with an electric hand mixer on high speed until stiff peaks form.

Step 9

Stir pudding a few times then spoon into individual serving dishes, top with whipped cream and garnish with shaved chocolate.