Preheat oven to 340° Fahrenheit (170° Celsius).
Prep a 17 by 11 inch (about 43 cm by 28 cm) baking pan with parchment paper on the bottom. Butter the sides. OR butter the bottom and sides, then dust in all purpose flour (I ran out of parchment paper last time and this worked great!).
For the Apfelkuchen batter, mix butter and sugar until creamy (about 5 minutes). Gradually add in the eggs, lemon zest (reserving the juice for the apples) and salt. Sift together flour and baking powder and mix in with the batter. Add in the milk to achieve a smooth consistency. Spread evenly onto the prepped baking sheet.
250 grams butter, 250 grams sugar, 4 eggs, 1 lemon, ½ teaspoon salt, 400 grams all-purpose flour, 4 teaspoons baking powder, ¼ cup milk
For the German apple cake topping, prep your apples by washing, cutting them in quarters and removing the core. I don't peel mine, but you can feel free to peel yours if you'd like. Cut your apples into ½ inch thick slices (about 1 cm thick). Toss them in the juice of your zested lemon to keep them from turning brown. Arrange in rows by slicking them into the batter.
5 apples
For the streusel, first start by beating together flour, almonds, butter, sugar and cinnamon with an electric mixer. Then briefly work the dough with your hands, forming your streusel. Keep in a cool place until ready to use.
60 grams all-purpose flour, 40 grams butter, 30 grams sugar, 30 grams sliced almonds, 1 teaspoon cinnamon
Evenly distribute the streusel topping over the apples. If you would like to keep your neat rows of apples more visible, you can stick with only adding the streusel topping between my rows of apple slices. That's what I did and it looks so lovely!
Bake for 32 minutes on the middle rack, then test to see if the cake is done. If you have an instant-read thermometer (this one's my favorite!), test the internal temperature. Around 210° F or 99° C is perfect! Remove from oven and allow to cool for 5 minutes before slicing and serving with some freshly whipped cream (I add a little vanilla extract and powdered sugar to mine). Guten Appetit!