Step 1

In a medium saucepan, whisk together the cornstarch, cocoa powder, sugar salt, and salt.

Step 2

In a separate bowl, combine the milk and egg.

Step 3

Gradually pour the milk mixture into the saucepan, whisking until thoroughly mixed.

Step 4

Heat the mixture, stirring constantly, over medium heat until it boils. Cook for 1 minute, then remove from heat.

Step 5

Stir in butter and vanilla extract.

Step 6

Pour the pudding into the suitable molds rinsed with cold water (the pudding can be taken out more easily).

Step 7

Chill.