These elegant confections make a perfect base for toppings like our Caramelized Pineapple or Warm Chocolate Sauce.
Preheat oven to 200 degrees. In the bowl of an electric mixer fitted with the whisk attachment, combine whites, lemon juice, and vanilla. Beat on low speed, gradually increasing to high, until soft peaks form, about 1 1/2 minutes.
Sprinkle sugar over the egg white mixture; beat on high speed until glossy peaks form, about 3 minutes. Sift cornstarch over mixture, and fold to combine.
Using two soup spoons, drop balls of meringue onto a parchment-lined baking sheet. Press down on center of each ball with one spoon to form a small cup.
Bake 1 hour. Reduce oven temperature to 175 degrees; continue baking until outside is dry and crisp and inside is chewy, about 1 hour more. Remove from oven; let cool completely.
Store in an airtight container at room temperature up to 1 day.