Donauwelle (“Danube wave”) is a classic German cake – Vanilla and chocolate, cherries and buttercream, this cake has got it all!
Donauwelle, like quite a few German cakes, is baked in a large baking tray and then cut into squares to serve. It’s made up of several different layers: Vanilla cake, chocolate cake with cherries, a German custard buttercream and finally a layer of chocolate.
The cherries get pressed into the chocolate cake layer before baking, which creates a wavy, swirly look when cut open. Together with the waves in the chocolate topping, this is where the wave part of the name originates. Why it is specifically called a Danube wave is not entirely clear.
German custard buttercream is slightly lighter and less sweet than traditional buttercream. It has a lovely custardy taste and is used in a lot of German cakes.
In Germany, cakes are traditionally eaten with coffee in the afternoon between lunch and dinner, usually on Sundays. This is called Kaffee und Kuchen (“coffee and cake”) and can be compared to the British afternoon tea, but without the savoury options and coffee instead of tea (although some people do prefer tea).
Kaffee und Kuchen is a perfect opportunity to catch up with friends and family in a relaxed setting. It can range from a simple chat over a cup of coffee and a slice of chocolate cake to a fully blown occasion with several different types of cakes and a choice of coffee and tea.
You can find all kinds of different cakes at Kaffee und Kuchen – including the internationally known Black Forest Gateau. You may also find other cream filled cakes, simple sponge cakes topped with fresh fruit, buttercream filled cakes or yeast based ones. And of course they need to be served with a good dollop of whipped cream, unless they are already filled with it that is!
One 40x30cm tray makes 20 squares
You will need
For the buttercream:
60g caster sugar
40g corn flour
3 egg yolks
1 tsp vanilla extract
250g butter, softened
For the cake:
250g butter, softened
200g caster sugar
Pinch of salt
1 tsp vanilla extract
375g plain flour
3 tsp baking powder
30g cocoa powder
1 jar of pitted sour cherries OR 2 tins pitted cherries in light syrup, drained well
For the topping:
350g chocolate, chopped
1 tbsp flavourless oil
- First, make the custard for the buttercream. Put the milk, caster sugar, corn flour, egg yolks and vanilla in a medium saucepan and put on a medium low heat. Slowly bring to the boil, whisking all the time. Once it has come to the boil, bubble for another 1-2 minutes, still whisking all the time. Take off the heat, transfer to a shallow dish and cover with cling film directly touching the surface. This will stop the custard from forming a skin. Put to the side to cool.
- While the custard is cooling, make the cake. Heat the oven to 180°C/gas mark 5 and line a 40x30cm baking tray with baking paper.
- Beat the butter with the sugar, salt and vanilla for about 5 minutes until light and fluffy. Add in the eggs one at a time, beating between each addition. Mix the flour and baking powder and fold into the mixture until you have a smooth batter.
- Spread just over half the batter in an even layer into the baking tray. Add the cocoa and milk to the remaining batter and mix until smooth. Spread the chocolate batter evenly over the vanilla batter. Spread the cherries out over the cake and lightly press into the batter.
- Bake for about 35 minutes until a skewer inserted into the cake comes out clean. Leave to cool in the tray.
- Beat the butter for the buttercream for about 5 minutes until really pale and light. Press the cooled custard through a fine sieve and then add to the butter bit by bit. Beat until you have a smooth, light buttercream. Spread the buttercream evenly onto the cooled cake. Put in the fridge for 20 minutes to firm up.
- Meanwhile, gently melt t he chocolate either in the microwave or over a hot water bath. Once melted, stir in the oil until smooth. This makes the chocolate a little more runny and easier to get in an even layer on the cake.
- Pour half of the chocolate over the cake and smooth out with a palette knife. Leave to set – this should be very quick, because the cake will be cold. Pour the second half of the chocolate and spread out. Wait a minute or two, until the chocolate is a little less runny, then take a fork or an icing comb with a zigzag edge and drag it through the chocolate to create a wavy pattern. Leave to set.
To cut this cake into squares, dip a knife in hot water and melt through the chocolate layer, then cut the cake. Will keep in the fridge for up to 3 days.