Preheat oven to 250 F (120 C)
Line two baking sheets with foil. Trace 3-1/2 inch ( 8-9 cm) circles on foil. Place egg whites in a bowl and place bowl in warm water for 3 minutes; remove. Add vanilla, cream of tartar, salt and 1/4 cup (50 mL) sugar. Beat with electric mixer until soft peaks form. Gradually add remaining sugar, 2 tbsp (30 mL) at a time, beating until sugar is completely dissolved and meringue is very stiff. Spoon meringue into circles on foil; spread with a spoon, building a rim. Bake 75 minutes or until meringues and crisp but not browned, and can be removed from foil. Turn oven off and leave meringues in the oven, with the door closed, 4 hours overnight.
In a medium saucepan, combine cornstarch and sugar. Stir in milk and chocolate. Bring to a boil over medium heat, stirring constantly, and cook 30 seconds. Beat half of the mixture into the egg yolks. Pour yolk mixture into saucepan. Cook, stirring over low heat 1 minutes, without letting it boil. Stir in vanilla. Transfer mixture to a bowl. Place a sheet of plastic wrap directly over filling and refrigerate until cold. Spoon cold filling into meringue shells. Cover with aluminum foil. Refrigerate 3 to 24 hours. Garnish with fruit before serving.