Directions:

Bring 4 cups of water to a boil.

Peel your apples, and keep them in water if your not going to immediately slice and use them.

Pour the boiling water over the apple slices

Cover and let sit for at least 10 minutes. This process will set the cell structure so it doesn't break down as much during cooking and get mushy. Also the cake doesn't take that long to bake so it helps to par cook the apples.
Alternatively you can saute the apples and half cook them.

Pre- Heat the oven to 350 degrees

Gather your dry ingredients

Mix the flour, baking powder, salt, and sugar in a separate bowl.

Gather your wet ingredients, egg whites, yogurt or sour cream, egg yolks, melted butter, vanilla.
I have put the yolks in a small blender as I will bend all the wet ingredients except egg whites.

Lemon peel in your apple kuchen is very German. I really like it but it is optional.
Add it if you like. You can also add it to the apples or the Streusel topping.

Mix the wet ingredients except the whites well in a food processor or together with the dry ingredients till just well blended. Do not overmix, we don't want a bread texture.

White the egg whites to stiff peaks.

Fold in the egg whites very gently.

Blend the Streusal ingredients together.

Pour the batter into a buttered and floured springform pan. You can use a pie pan or
square glass baking dish also.

Add the cinnamon, sugar, vanilla and the lemon peel if you want. if the apples seem wet like these were you
can add a tblsp flour.

Place the apples gently on top of the batter. I did a circle but you can place them any way you want.

Top with the Streusel, and slivered almonds if you wish.

This is an option. I up the recipe by a half and made some individual ones.

Bake for 30- 45 minutes until the batter is set. The internal temperature should be about 200 degrees.