Peel and core the apples and slice them into sixteenths and set them aside in bowl of water with some lemon juice squeezed into it to keep the apple slices from browning. (I actually cut mine even thinner as my apples were a bit on the large side)
Sift flour with salt (and the baking powder if required).
Using a mixer, cream ½ cup of the butter and the 1 cup of white sugar until smooth.
While continually mixing, add the egg yolks one at a time alternating with a tablespoonful of flour in between yolks to achieve a smooth and creamy consistency in the mix.
Add the rest of the flour in stages, alternately adding the milk in stages as well. Then add the vanilla extract and lemon rind and mix until the batter is smooth.
In a separate mixing bowl, whip the egg whites into stiff peaks and then using a spatula, carefully fold them into the batter.
Butter the sides of a pie baking dish and pour in the finished batter.
Arrange the apple slices in a perpendicular fashion overtop of the batter in a circular pattern to form an outer ring of apple slices. Fill the center of the ring with any remaining slices.
Melt the remaining ¼ cup of butter along with the ¼ cup of brown sugar, mix in the cinnamon and pour the mixture over the apple slices in a circular fashion, making sure to distribute it evenly in a long even stream.
Place baking dish in an oven pre-heated to 350° F. and bake for approximately 60 minutes (mine was 50-55).Let the Milopita stand to cool for at least a couple hours before serving.