01 - Whisk together sugar, cocoa powder, cornstarch, and salt in a medium saucepan. Gradually add whole milk while whisking to fully dissolve the dry ingredients.
02 - Place saucepan over medium heat and cook, whisking constantly, until mixture thickens and bubbles, about 5 to 7 minutes.
03 - Remove from heat and stir in chopped semi-sweet chocolate and vanilla extract until chocolate is completely melted and mixture is smooth.
04 - Pour pudding evenly into four serving dishes. Cool slightly, then cover the surface directly with plastic wrap to prevent skin formation.
05 - Refrigerate for at least one hour until fully chilled.
06 - In a chilled bowl, beat heavy cream, powdered sugar, and vanilla extract until soft peaks form.
07 - Top each chilled pudding with a dollop of whipped cream before serving.