Line a baking sheet with parchment paper and preheat the oven to 285ºF (140ºC).
Beat the egg whites and vanilla in a large bowl until stiff peaks form.
Add the sugar, 1 tablespoon at a time, continuously beating, until the meringue is smooth and glossy.
Divide the meringue into 8 mounds on the parchment-lined sheet. Gently flatten the centre of each meringue with the back of the spoon to form small nests.
Bake the meringues for about 1 hour and 15 minutes (for softer meringues, reduce the bake time by 15 minutes).
Let the meringues cool in the oven with the door propped slightly open for a couple of hours before removing to a cooling tray.
Fill the cooled nests with lemon curd, fresh berries, whipped cream, or anything else you like.
Notes
If you don't have vanilla, ground cardamom makes a nice substitution. Add it with the last tablespoon of sugar when mixing.