Vanilla or Chocolate Pudding

From Martha Stewart

Rediscover homemade pudding's comforting simplicity, then see how versatile it can be. Choose one or the other, or make them both!

Yield Serves 4

Ingredients
    2/3 cup sugar
    1/4 cup cornstarch
    1/4 teaspoon salt
    1/3 cup unsweetened cocoa powder
    2 1/2 cups milk
    4 large egg yolks
    2 tablespoons unsalted butter, cut into pieces
    1 teaspoon vanilla extract

Method
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.
   
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.
   
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.