Preheat the oven to 180℃/360℉. Line a baking pan with baking paper and set aside.
Put egg whites and sugar into a large bowl, lightly beat with a whisk until frothy but not stiff.
Add rolled oats, chopped dark chocolate, coconut oil. Stir until it's well combined.
Spoon onto a baking tray and shape into rounds. You don't need to leave so much room between the cookies because they won't spread.
Bake for 15 to 20 mins, or until golden brown. Remove from the oven and let cool for 5 minutes before transferring to a cooling rack to cool completely.