Danube Wave Cake

Donauwellen Kuchen, also called “Snow White Cake", is a sheet cake that is popular in Germany and Austria. Soft, fluffy and moist vanilla sponge with hints of chocolate and morello cherries. The iconic waves of this cake set it apart from the rest. Bursts of morello cherries are a sweet surprise you can't miss out on! Topped with creamy, dreamy german buttercream that is mild in flavour but bang on when it comes to texture. And you can't miss the perfect layer of chocolate ganache that ties all these elements together to create a cake so magnificent it's love at first sight!

Serves:12

Ingredients

Sponge

Vanilla

2 cups Flour

2 tsp baking Powder

½ tsp baking Soda

Pinch of Salt

1 ⅓ cup granulated Sugar

3 Eggs

125g Buttermilk

170g unsalted Butter

2 tsp Vanilla extract

Chocolate

¼ cup Cocoa powder

30g Buttermilk

16 Morello cherries

German Buttercream

3 Egg yolks

⅓ cup granulated Sugar

2 tsp Vanilla extract

¾ cup Milk

¾ cup Heavy Cream

4 tbsp Cornstarch

¼ cup Water

1 cup unsalted Butter

Chocolate Ganache

1 ½ cups dark Choco-chips

1 ½ cups Heavy Cream

Method

Step 1- Vanilla Sponge

Preheat the oven to 170℃ and line a 9x9 inch baking tin with parchment paper. Add butter to a mixing bowl and with a hand beater on medium cream the butter for 2-3 minutes or till it doubles in volume. Then add ¼ cup granulated sugar at a time to the butter and beat till fully incorporated. Scrape down the bowl.

Step 2

Add one egg at a time to the bowl and beat till fully incorporated. Then add in vanilla extract and beat for 30 seconds. Separately sift flour, baking soda, baking powder and salt. Add ⅓ of the dry ingredients to the batter and beat till incorporated. Followed by ⅓ of buttermilk and repeated until all the dry and wet ingredients are added to the batter. Scrape the bowl from time to time. Pour the batter into the lined baking tray, reserving ¼ of the batter.

Step 3- Chocolate Sponge

Add cocoa powder and buttermilk to the reserved batter. With a rubber spatula, fold the ingredients in. Then add half the batter to the baking tin and spread it evenly with an offset spatula. Add morello cherries on top and gently push them down. Then add the rest of the batter and spread over the cherries with an offset spatula.

Step 4

Bang the tray against the counter several times and place it in the oven. Bake the cake for 35-40 minutes or until an inserted toothpick comes out clean. Then take the tray out and let the cake rest in the tin until it cools to room temperature. Then cling wrap the tray and place in the refrigerator for 2 hours or till ready to frost.

Step 5- German Buttercream

Add milk and heavy cream to a saucepan, place medium heat, and bring to a light simmer. Meanwhile, add egg yolks, granulated sugar and vanilla extract to a heatproof bowl. Whisk till smooth. Once the milk and heavy cream reach a light simmer, take the saucepan off the heat.

Step 6

Add ¼ cup of the simmered liquid to the heat-proof bowl and whisk continuously till smooth and lump-less. Then add back to the saucepan and place it back on medium heat. Whisk continuously till all the ingredients are fully combined. Then add cornflour and water to a bowl and mix together. Pour the cornflour slurry into the saucepan and then whisk continuously till the custard thickens or till it coats the back of a spoon.

Step 7

Add the custard to a heat-proof bowl and cling-wrap the surface of the custard and let it cool down to room temperature. Once cool, place it in the refrigerator for 2 hours or overnight. After the custard sets, remove it from the refrigerator for 30 minutes before making the frosting.

Step 8

Then add butter to a mixing bowl, and then with a hand beater on medium, cream the butter for 3-4 minutes or till the butter doubles in volume. Then add in your custard and beat together until fully incorporated might take up to 4 minutes. Once the buttercream thickens and holds its shape, stop and scrape down the bowl.

Step 9

Take the baking tray out of the tin. Brush the cake with morello syrup, and then add the buttercream on top of the cake. With an offset spatula, evenly spread the buttercream. Then cling wrap the tin again and place it in the refrigerator for 2 hours or until the buttercream sets.

Step 9- Chocolate Ganache

Add heavy cream to a saucepan and place it on medium heat. Bring the heavy cream to a light simmer, then take it off the heat. Pour the heavy cream into the chocochips and let them rest for 10 minutes. Then whisk the heavy cream and chocolate together 3-4 times for 5 minutes. Taking 10 minutes intervals. Once the ganache is thick and lump-free, let it cool down for 10 minutes.

Step 10

Then take the tray from the refrigerator and add the chocolate ganache to the frosting. With an offset, spread the ganache evenly. Take a fork and form a wave-like texture on top. Then cling wrap the tray and place it back in the refrigerator for 2 hours or till the ganache sets.

Step 11- Serving

Take the cake out of the refrigerator 30 minutes before serving. Cut into the cake with a sharp, warm knife. Cut the cake into 12 bars and serve with fresh or morello cherries from the jar.

Tips

1. All ingredients need to be at room temperature.

2. Ensure that the sugar completely dissolves in the butter but do not overbeat the mixture.

3. You can replace buttercream with whole milk.

4. Add 1-2 tbsp extra buttercream to the chocolate sponge if you feel the batter is too thick.

5. Gently push the morello cherries to create a beautiful wave effect but don’t press too hard.

6. Let the cake cool down completely before placing it in the refrigerator.

7. Whisk the yolk continuously after adding boiled milk and cream to avoid scrambling.

8. Ensure your cornflour slurry is lump-free.

9. Stir the custard occasionally to avoid sticking to the pan's bottom.

10. If you want a sweeter buttercream, you can add ½ - 1 cup of icing sugar to the frosting after beating in the custard.

11. Make sure to use a heat-proof bowl when making the ganache.

12. If the heavy cream boils over, wait until it cools down before adding it to the chocolate.

13. Only remove the cake after all the layers are set. It’s easier to assemble the cake within the tin.

14. Rest the cake overnight in the refrigerator after assembly for best results.