Time needed: 45 minutes.

Ingredients list

Pie Crust:
8.8 oz (250 g) all-purpose flour
2.8 oz (80 g) powdered / confectioners sugar
5.3 oz (10 – 1/2 tbsps / 150 g) unsalted butter
2 tsps baking powder
1 egg yolk

Filling:
about 5 apples
ground cinnamon
vanilla flavored sugar
raisins (optional)

Sponge Cake:
4 egg whites
3 tbsps powdered / confectioners sugar
3 egg yolks
3 tbsps all-purpose flour

1. Prepare the Apples

   Wash, cut in quarters, peel, and remove the cores from the apples. Set aside.

2. Preheat the Oven

   Don’t forget to turn on your oven ahead, and preheat it to 355°F or 180°C.

3. Make the Pie Crust

   Mix the Pie Crust dry ingredients and then blend with the softened butter and the egg yolk. (Reserve the egg white for later.) Form a homogenous dough ball.

4. Fill the Form

   You can use either your favorite round pie form, or like me, just use a simple 13×9″ baking pan.
   You can line it with baking paper, but it is not really necessary. There should be enough butter in the crust, so as not to stick to the pan. Roll out the dough flat and line the bottom of your pan.

5. Make the Filling

   Shred the apples and spread them evenly on top of your unbaked crust.

6. Add Flavor

   Sprinkle generously with ground cinnamon and vanilla-flavored sugar. If you like it, add some raisins too. They go great with apples and cinnamon!

7. Bake the filled Crust

   Place the pan in the preheated oven (355°F/ 180°C) and bake for about 15 minutes until the apples start to sizzle, turn golden and smell nice.

8. In the Meantime Make Sponge Batter

   Separate the rest of the eggs and put the 4 egg whites into a big bowl. Whip on high speed until stiff peaks form… about 10 minutes. Then slowly stir in the sugar. Then gradually add the egg yolks with flour. You can do this gently by hand. Or slowly in a blender with a whisk.
   
   Don’t forget to occasionally scrape the sides of the bowl so your dry ingredients are evenly blended in.
   
   You should be just about ready when your timer for the pie crust goes off.

9. Cover with Sponge Batter

   Remove the baked crust with apples from the oven and pour the sponge batter right over it. Spread it evenly using a spatula and return back to the oven as soon as you can.
   Turn down the heat to about 300°F or 150°C and bake for about 20 minutes until the sponge cake turns golden and stiff.

10. Serve

    After you pull out the pie from the oven, the sponge cake top will eventually soften and drop a little because of the steaming apples, but it is ok. I mean, you could probably jump through some hoops of gradual cooling, like when baking a cheesecake, BUT I think this dessert tastes best warm anyway.

11. Enjoy!

    So just let it cool down slightly for easier handling, cut it to pieces, dust it with powdered sugar and serve!
    Curl up with your hot drink under a soft warm blanket and enjoy a warm and delicious Apple Sponge Pie!