Cake: Preheat oven to 180 degrees C. Grease and flour a 23x33cm cake tin.
Sift together flour and baking powder.
Whisk the egg whites to soft peaks then continue whisking while slowly adding the sugar until stiff peaks have formed. Fold in egg yolks until evenly mixed then fold in the flour mixture alternately with the orange juice.
Pour batter into the prepared cake tin.
Bake cake in preheated oven until the top has turned golden brown and a toothpick inserted into the centre comes out clean; about 40 minutes.
Coconut Soak: In a small bowl stir together the milk, coconut milk and sweetened condensed milk.
To Serve: When the cake is done remove from the oven and use a fork to poke all over the top of the cake in 2cm intervals. Evenly pour the milk mixture over the cake then sprinkle with coconut flakes.
Chill the cake in the refrigerator until cold, about 3 hours.