Chocolate Velvet Pudding

Whisk egg, condensed milk, cocoa, cornstarch and salt in a heavy saucepan until smooth. Gradually whisk in milk. Bring to a boil over medium-low heat, whisking constantly, until thickened, 7 to 9 minutes.

Remove from the heat; add chocolate and vanilla, whisking until the chocolate melts. Transfer to a bowl. Place plastic wrap directly on the surface to prevent a skin from forming. Serve warm or refrigerate until ready to serve.