Pre- heat oven 350F -180 C. Line a 9" round springform tin with baking paper.

Add 6 eggs to an electric mixer with the whisk attachment fitted. Beat on high for 1 minute until foamy. With the mixer on gradually add sugar and beating on high for 10 minutes, or until thick and fluffy ribbon forms.

Peel apples, core, quarter and slice into small chunks.

In a medium bowl add flour and baking powder. Sift dry ingredients into egg batter, folding gently with a spatula until all the flour is incorporated. Add vanilla and mix till incorporated. Fold in sliced apple and reserve 1 cup for the top. Fold until just combined then pour batter into prepared tin. Spread evenly with a spatula. (do not tap tin) and scatter remaining apple evenly over the top. Bake for 55 minutes. Top will be golden brown.Remove from oven and allow to cool in the tin for 15 minutes. Slide a thin knife or spatula around the edges of the pan to loosen the cake and then transfer cake to a platter to cool completely. Sprinkle icing sugar over top and serve.