Preheat the oven to 200°C. Grease and line a baking tin.
Sieve the flour, baking powder and cinnamon into a bowl.
Peel the apples, then grate them using a coarse cheese grater.
Separate the eggs.
Mix the egg yolks with the sugar, grated apple and oil.
Beat the egg whites until you get peaky foams, then gently stir in the apple mixture. Transfer the batter into the baking tin, and spread it out evenly.
Bake for about 45 minutes. When it's golden brown and the sides come away from the walls of the tin, the cake is ready.
Allow it to cool in the tin, then slice it into cubes. Before serving dust it with icing sugar mixed with cinnamon.