Preheat oven to 180℃ or 350℉
Spray and line a 25cm x 38cm baking tray with baking paper
In the bowl of an electric mixer fitted with a whisk attachment, whisk egg whites and cream of tartar on medium speed, until soft peaks form
Gradually add the caster sugar, 1 tablespoon at a time and continue beating for 30 seconds between additions. Once all the sugar has been added, keep mixing until meringue is smooth and glossy (around another 10 minutes).
Take a small amount of meringue with your fingers to check if the meringue is smooth. If it's still gritty, keep whisking.
Spread mixture onto your prepared tray, then sprinkle with almonds.
Bake for 14-15 minutes, until lightly golden. While it's baking, prepare another sheet of baking paper by sprinkling it with another tablespoon or 2 of caster sugar.
Once cooked, remove the meringue from the oven and turn over onto the prepared baking paper, almond side down. Leave to cool