No, this is not a German insult but a cake. In fact its full name is Gefüllter Streuselkuchen, which literally translated means Filled Crumble Cake. The combination of buttery yeast cake, sugary crumble and cool vanilla custard is heaven on a plate. The Streusel is a traditional Luxembourg thing and you can buy individual little Streusels in every bakery. Or at least you could when I was a child. Don’t worry, it’s actually much easier to make than it looks and the cake is very forgiving, so even if the shape isn’t quite perfect, it just adds to the homely look. The whole assembled cake keeps much longer that you might think and a nice slice right out of the chiller will be almost as good a week later as when you first baked it. Neither the crumble nor the cake will go soggy.
For the Cake Starter:
- 80g plain flour
- 8g dry yeast
- 80ml just warm milk
If your milk is cold, heat it to reach just above blood temperature. If you put a finger in the milk, it should feel just warm. Mix the flour and yeast in the bowl of a stand mixer, add the milk and stir to mix well. Cover and leave to rise for 30 minutes until about doubled on size.
If you are clever, you don’t do what I did, but go out and buy the correct cake tin, which will be either a 24cm spring form, or loose bottom tin. As I didn’t have one, I decided to make a sleeve out of parchment paper to go around that little tin you see in the picture above. It’s a hell of a lot of bother and you’ll need to make 2 separate ones; one for baking and one for filling the cake with custard. Not going to do that again!
For the Cake Dough:
- 180g plain flour
- 40g caster sugar
- 4g fine sea salt
- 80ml just warm milk
- 1 egg
- 40g butter (very soft, but not melted)
Sift the flour into a bowl, add the sugar and salt and mix. Lightly beat the egg and mix it with the warm milk. Make sure your butter is very soft, or it will be difficult to mix into the dough. Use the hook of the stand mixer to stir the air out of your starter, fit the bowl and hook to the mixer and turn the speed to low. Now add the flour mix, then the milk and egg. Once the dough has come together, turn the speed one notch up and leave to knead for ten minutes. Now add the butter and knead until the dough has absorbed the butter and the dough is smooth, about 5 minutes in total. Cover and leave to rise for 30 minutes.
While the dough is rising, make the Streusel Topping and keep it at room temperature.
For the Streusel Topping:
- 50g butter at room temperature
- 100g caster sugar
- 100g plain flour
Mix the flour with the sugar and rub the butter into it with your fingertips. You are basically making crumble.
Finish the Cake:
Knock the dough back and shape it into a rough ball, put it into your cake mould and flatten it with moistened hands. Make sure the top of the dough is quite wet. This will help the topping to stick to it. Scatter the Streusel Topping over the dough and leave to rise another 20 minutes, then bake at 180ºC for 45 minutes.
For the Custard Filling:
- 600ml milk
- 2 tsp vanilla essence
- 6 egg yolk
- 120g caster sugar
- 35g corn starch
- 12g gelatine
- 3 Tbsp boiling water
Bring the milk to the boil in a saucepan. While this is heating up, weigh the sugar into a bowl and strain the corn starch on top, then mix with a whisk to get an even, lump free mix. Whisk the vanilla essence into the egg yolks, then whisk the sugar corn starch mixture in.
Pour three tablespoons of boiling water into a bowl and sprinkle the gelatine into the water. Stir with a spoon to dissolve completely. Do not whisk, or you’ll get a bowl full of foam.
Once the milk is just starting to boil, take it off the heat and leave for a minute, just to cool it a little. Slowly stir the hot milk into the egg mixture, then return it to the saucepan and heat it. Keep stirring with your whisk and make sure to reach into all the corners and not burn any part of the custard. We are going to strain it later, but any burnt part will give the whole custard a rather nasty flavour.
You will see the foam slowly disappearing and that is an indication that your custard is about to bubble. At the very first indication of a bubble, turn down the heat and continue to stir for just one minute. Strain the custard into a bowl, cover with cling film, making sure the film touches the surface of the custard and leave to cool down for an hour, or until just warm to the touch.
Now cut a lid off your Streusel. You want the top to be about one third of the total height. So 2/3 bottom 1/3 top. Don’t worry if some of the crumble falls off. There will be plenty left. If you did it all right, your cake will have a lovely, airy texture, but still be quite firm to the touch.
Place the bottom of the Streusel into the cake tin and strain the custard on while it is still just warm. Close your custard sandwich with the top of the cake, cover with cling film and refrigerate. This cake will easily keep for a week in the chiller, so you can make it a few days in advance.