Lemon chili crumble cake (Streuselkuchen)

This is another German cake recipe from Dr Oetker that I've adapted to make with ingredients available in the UK. The original is available in German on https://www.oetker.de/rezepte/r/zitronen-chili-streuselkuchen. My cake tasted better on the second day than the first, possibly because I hadn't left it to cool for long enough before eating the first slice.

It makes about 12 generous pieces or 16 smaller ones, and you will need a 26 cm springform cake tin to make it in.

Crumble ingredients:

½ - 1 small red chili pepper (if you use one that is too mild, you won't notice it at all)

300 g spelt flour

60 g brown sugar (the original uses vanilla sugar, so feel free to use vanilla sugar (i.e. sugar that's been sitting with a vanilla pod in it) here)

Peel of 1 -2  lemons

150 g soft butter or margarine (plus a little extra for greasing)

100 g chopped almonds

Filling ingredients:

250 g apples (about 2 to 2 1/2) - I used golden delicious 

500 g quark (ideally 40% fat, but actually any you can get)

200 g sour cream (highest fat available)

80 g brown sugar

37 g custard powder

3 medium eggs

1. Grease the 26 cm springform cake tin. Preheat the oven to about 170 °C/fan 150 °C.

2. To make the crumble, clean the chili pepper of seeds and chop very finely (it's advisable to wear rubber gloves to do this). 

3. Place the spelt flour in a mixing bowl and add the remaining crumble ingredients. Using a mixer (pastry hook or similar), mix on low speed until crumbles form. (If you haven't left the butter out of the fridge long enough for it to go soft, you either need to wait until it does or rub it into the flour like you would for pastry first, before adding the other ingredients)

4. Spread a good half of the crumble on the bottom of the springform cake tin and press down. 

5. Place the tin on a rack in the bottom third of the oven and bake for around 15 minutes.

6. Put the tin with the pre-baked base on a cake rack and allow to cool.

7. Press a good half of the remaining crumble mixture into the springform cake tin to form a 3 cm high rim.

8. Other than the apples, put all the the remaining filling ingredients in a bowl and mix well.

9. Wash the apples, core them and optionally peel them (I did, but the original recipe mentions neither peeling nor coring). Cut them into small cubes and spread these on the base.

10. Pour over the filling mix, then sprinkle the remaining crumble on top. 

11. Put the cake into the bottom third of the oven and bake for about 50 minutes.

12. Loosen and remove the sides of the springform cake tin. Let the cake cool on the bottom of the tin on a cake rack for at least 2 hours.