Preheat the oven to 175C/350F. Line and grease a 12cm x 24 cm loaf tin.
Place the egg whites in the bowl of a kitchen stand mixer with a whisk attachment fitted.
Whisk the egg whites on medium until soft peaks form.
Continue to whisk on medium and slowly add the maple syrup 1 tablespoon at a time until all added and stiff peaks form.
Add egg yolks and then milk and whisk until combined.
In a separate bowl, sift together the dry ingredients.
Sift the dry ingredients over the egg mixture and fold in gently.
Be careful note to over mix, but ensure that the coconut flour is mixed in well.
Pour the mixture in to the prepared tin.
Bake for 12 - 15 minutes, or until cooked through.
Allow the sponge to cool in the tin.
Once cool invert cake onto a serving tray.