WHY 5 ?! Because this experimental recipe is also a precise mathematical equation. It requires 5 times the amount (or weight) of thinly sliced round apple slices (cored and peeled) as compared to the rest of the 5 other main ingredients which are precisely equal amounts of butter, sugar, eggs, milk and flour (with small additions of baking powder, vanilla, cardamom and salt).

*in other words :

100% of APPLE CAKE N°5 = 50% apples + 50% batter

**or to break it down even further :  

50% apples + 10% butter + 10% sugar + 10% eggs + 10% milk + 10% flour.

The apples are not pre-baked nor cooked because they are sliced extremely thinly and plunged into ice-cold lemony water and remain raw before being shaken off and drained and going into the batter, creating a multi-layered cake of alternating fruit slices and batter. It reminds me of a horizontal fruit flan or a clafoutis and/or, after some research to better understand why this experiment worked, an Italian-style bolzano apple cake (or even an invisible cake which meant absolutely nothing to me initially but I then understood that it's because it has so little batter compared to the fruits, it's the batter that seems invisible).

Here's my “mathematically reinterpreted” and perhaps improved version.

The addition of flaked almonds on top, with some light brown sugar that slightly caramelizes as it bakes adds an additional crunchy top layer, lightly sprinkled with icing sugar just before serving in thin slices, revealing the fresh-tasting and still firm yet tender  enough apple slices and the creamier baked cake batter that surrounds them and holds them together.

If you’re like me, you’ve probably ended up with bags & bags & kilograms & kilograms of autumn apples, so make this, it's really good, and it also frees up storage space . . . :)