Heat oven to 225 degrees F. Line a baking sheet with parchment paper.
Place egg whites in a stand mixer bowl fitted with a whisk and whip until frothy.
Mix sugar and cornstarch together. Gradually add sugar to the beaten egg whites and continue beating until mixture is glossy and forms firm peaks. Stir in the vanilla.
Melt chocolate and heavy cream in a double boiler or in the microwave. Stir until chocolate is completely melted and smooth.
Add the chocolate and meringue into to a pastry bag and pipe onto a parchment lined baking sheet. Alternatively, you can drizzle the chocolate on top of the meringue and use a spoon to drop mounds onto the baking sheet.
Bake meringue for 1 hour and then turn off the oven and leave the meringues inside for an additional hour. Store meringues in an airtight container in the refrigerator.
Serve with whipped cream, hot chocolate sauce and/or vanilla ice cream.