Directions

1. Place a fine-mesh sieve over a medium bowl; set aside. In a medium saucepan, off heat, whisk together sugar, cornstarch, and salt. If making chocolate pudding, add cocoa powder. Very gradually (a few tablespoons at a time) whisk in milk, taking care to dissolve cornstarch. Whisk in egg yolks.
2. Whisking constantly, cook over medium heat until the first large bubble forms and sputters. Reduce heat to low; still whisking, cook 1 minute. Remove from heat; immediately pour through sieve into bowl. Stir butter and vanilla into hot pudding.
3. Place plastic wrap directly on surface of pudding (to prevent skin from forming); chill at least 3 hours and up to 3 days. Before serving, whisk pudding until smooth; divide among four serving dishes.