Heat the oven to 180C/fan 160C/gas 4. In a clean bowl, whisk the egg whites until stiff then gradually add the sugar, whisking continuously until thick and glossy. Sift in the flour, then fold into the egg whites with the coconut until completely combined.
Using an 8cm pastry cutter, squash spoonfuls of the mixture onto a baking tray lined with non-stick baking paper or silicone plastic sheets – you may need to do this in two batches. Bake for 15-18 mins until golden around the edges and just starting to brown on top. Leave to cool, then transfer to a rack.
While the macaroons are cooling, melt the chocolate in a microwave or over a pan of hot water and leave to cool slightly. Cover the smooth side with chocolate and leave to set in the fridge. The macaroons will keep in an airtight container for 2 days.
Coconuts aren’t the easiest thing to crack open. Wrap them in a cloth to keep them steady, then a hefty whack with a hammer should do the trick. For a more child-friendly treat, coat these macaroons in milk or white chocolate. Or, you could make these a lot smaller and serve them with coffee at the end of a dinner party.