In a large bowl, cream the butter with half the sugar until creamy.
Add the coconut, the flour and the lemon zest. Mix until well blended.
In a separated bowl, beat the egg whites until foamy, add the half of the sugar and beat until stiff peaks form.
With a spatula combine the coconut mixture and the egg whites mixture, until just combined.
Spoon the batter in a lined baking tray (leaving 2 cm between).
Bake in a previously pre-heated oven at 180°C for 10 minutes or until lightly golden.
Sprinkle with some extra coconut or powder sugar.