Danube Waves Cake (Donauwellen Kuchen)

Danube Waves Cake (or Donauwellen Kuchen) is a German cake flavored with chocolate, vanilla, and cherries. It’s a delicious way to celebrate Oktoberfest or just a regular Thursday!

Do I ever have a treat for you today!!! And also a whole lot of instructional photographs. . .but we’ll get to those in a bit.

Today we’re kicking off Oktoberfest in style with some delicious German recipes AND A GIVEAWAY! One lucky person (over the age of 21) in the contiguous 48 states will win a case of Oktoberfest beer from Prost Brewing.

When my friends Milena and Chris asked if I’d want to participate in their Oktoberfest Bash this year, I immediately said OF COURSE! Every year for Oktoberfest, they host a blog party where bloggers contribute German recipes; scroll down to find more awesome German food from a great group of bloggers.

Just weeks before they asked, I’d seen a picture of a German cake called Donauwellen Kuchen (or Danube Waves Cake) that I knew would be the perfect addition, if only I could get the beautiful layers right.

Did you happen to catch those layers? Silly question. They’re hard to miss. Donauwellen Kuchen is made with layers of chocolate and vanilla cake, tart cherries, German buttercream, and chocolate ganache. When the cake bakes, the batter forms beautiful waves, which apparently look like the waves on the Danube river. 🤷🏻‍♀️

Incidentally, another name for Donauwellen Kuchen is “Snow White Cake.” I honestly don’t get why. But it’s delicious and I don’t really need to understand the name–I just need an extra-large slice and a fork with which to eat it.

What is German buttercream?

Did you do a double take when I mentioned German buttercream above? When I was researching the Danube Waves Cake so I could replicate it, I was like WHAT? I’ve never heard of German buttercream before!

Now that I have, my life may never be the same. German buttercream is frosting made with PUDDING! Yes, first you make a pudding/pastry cream, then when it’s cool, you whip it with butter and powdered sugar. The result is the creamiest,most luscious frosting you’ve ever met. The Germans do their frosting right, I tell you.

How to make German buttercream

Now that I’ve tempted you with a description let’s talk about how to make it. Quick and easy, German buttercream is not. But it’s worth the extra effort!

Combine cornstarch and sugar in a bowl next to the stove. Set two eggs in a second bowl, also next to the stove. Combine whole milk and more sugar in a small saucepan and bring that to a simmer.

Once the milk has simmered, whisk the cornstarch-sugar mixture into the eggs.

Whisk a scant quarter cup of the hot milk into the egg mixture until combined, then drizzle the remaining milk into the eggs in a continuous stream (like in the first pic above). Whisk the mixture constantly during this process—whisking keeps the eggs from scrambling.

Return the mixture to the saucepan and cook, stirring constantly with a rubber spatula. The mixture will start to clump up; that’s just fine! Once it starts to clump, turn the heat as low as it will go and stir vigorously with a whisk until the mixture is very smooth and lump-free.

Getting the lumps out takes some elbow grease but if you don’t get them out now, your frosting will turn out lumpy and unpleasant. (I speak from experience.) Remove from the heat and stir in butter (second pic above).  At this point your pudding should be completely smooth, like in the third pic above.

Chill the pudding in the fridge for at least 90 minutes (or overnight). After it’s fully chilled, bring it back to room temperature.

It is key that both your pudding and your butter are at room temperature. If the pudding is too hot, it will melt the butter; if either is too cold they will not blend together nicely.

Transfer your room temp pudding to the bowl of a stand mixer fitted with the whisk attachment and beat until thick and creamy  (first pic up above). Add the butter 1/2 a tablespoon at a time until it’s all mixed in, then mix in powdered sugar, vanilla, and salt and beat until smooth. And finally you’re done!  You end up with very smooth, very fluffy frosting like in that last pic.

How to make Donauwellen Kuchen

The frosting is covered—now onto the cake layer! AKA, the vehicle to deliver our German buttercream. The cake itself is actually very straightforward.

Beat butter in a large mixing bowl until smooth. Add sugar and vanilla and beat to combine—the mixture will be really crumbly, as in the second picture above. It will smooth out after you mix in the egg whites, as in the third pic above.

Next you’ll mix in your dry ingredients and buttermilk until incorporated.

Baker’s tip: If you don’t want to buy a whole carton of buttermilk for your Danube Waves Cake, you can substitute 1 1/3 cups whole milk mixed with 1 tablespoon of lemon juice or white vinegar. Let the mixture sit for 5 minutes before using it.

Pour three-quarters of the batter into a 13-by-9-inch pan.

Mix cocoa powder and milk into the remaining batter. Dollop the chocolate batter over the top of the vanilla batter and smooth with an offset spatula. Don’t swirl the two batters together! They’ll form waves on their own.

Top with drained tart cherries and bake for about 35 minutes, then cool completely before frosting your cake. Don’t try frosting the cake while it’s still hot or you’ll melt the frosting you just worked so hard on.

Spread the buttercream over the cooled cake, then refrigerate to set the frosting. Top with chocolate ganache, chill to set that, and you’re done!

OK, I’ve just bombarded you with about a million pictures and thousands of words and for that I apologize.

But I don’t apologize for this cake. You’ve GOT TO TRY Donauwellen Kuchen for yourself. A taste is worth a thousand words. I think that’s how the saying goes 🙂

More Oktoberfest recipes!

As promised, here are recipes from my blogger friends so you can celebrate your tastiest Oktoberfest yet.  Check out last year’s Oktoberfest post for even more!

Did you make this Donauwellen Kuchen? That’s great! Let me know what you think with a comment and a rating below. And post a pic on Instagram too! Tag @theitsybitsykitchen so I can see your creations! 

4.95 from 20 votes

Print

Danube Waves Cake (Donauwellen Kuchen)

Prep Time

1 hr 20 mins

Cook Time

1 hr

Cooling time

5 hrs 40 mins

Total Time

8 hrs

 

Danube Waves Cake is a delicious German dessert flavored with chocolate, vanilla, and cherries.

Course: Dessert

Cuisine: German

Servings: 16

Author: Kelsie

Ingredients

German buttercream:

• 1/2 cup granulated sugar divided
• 1/4 cup cornstarch
• 2 large eggs
• 1 cup + 3 tablespoons whole milk
• 2 tablespoons unsalted butter at room temperature
• 1 1/4 cups unsalted butter at room temperature
• 1 cup powdered sugar
• 1 1/2 teaspoons vanilla extract
• 1/8 teaspoon salt

Cake layer:

• 2 cups all-purpose flour
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon salt
• 1 3/4 cups granulated sugar
• 2 teaspoons vanilla extract
• 4 large egg whites at room temperature
• 8 tablespoons unsalted butter at room temperature
• 1 1/3 cups buttermilk*
• 1/4 cup cocoa powder
• 1 tablespoon whole milk
• 1 15-ounce can tart cherries in water, drained well

Chocolate topping:

• 5 ounces dark chocolate finely chopped
• 1/2 cup heavy cream
• 1 tablespoon light corn syrup

Instructions

German buttercream:

1. Stir 1/4 cup of the sugar together with the cornstarch in a small mixing bowl and set aside.
2. Crack the eggs into a medium heat-proof bowl. Whisk the eggs together and and set the bowl next to the stove.
3. Combine the milk and remaining 1/4 cup of sugar in a small saucepan set over medium heat and bring to a simmer, stirring occasionally.
4. Once the milk has come to a simmer, whisk the sugar-cornstarch mixture into the eggs until smooth.
5. Whisking the eggs constantly, add a scant 1/4 cup of the hot milk to the eggs. Still whisking constantly, pour the remaining milk into the eggs in a slow stream.
6. Return the mixture to the saucepan and set pan over medium-low heat. Cook, stirring constantly with a rubber spatula, until the mixture thickens a bit—it will start to get lumpy.
7. Turn the heat to low and switch to stirring with a whisk. Whisk vigorously until the mixture is very thick and smooth—if you don’t get your pudding completely smooth, you’ll have lumps in your frosting.
8. Remove from the heat and stir in the 2 tablespoons of butter.

9. Scrape the pudding into a shallow mixing bowl and press plastic wrap directly on the top of the pudding. Chill in the fridge for 90 minutes to 2 hours (or until thoroughly chilled).  You'll finish the frosting later.  While the pudding is chilling, make the cake.

Cake layer:

1. Preheat the oven to 350 degrees. Spray a 13- by 9-inch baking pan with cooking spray and set aside.
2. Whisk the flour, baking powder, baking soda and salt together in a small mixing bowl and set aside.
3. Beat the butter in a large mixing bowl with an electric mixer set to medium until very smooth. Beat in the sugar and vanilla until well combined (mixture will be crumbly). Add the egg whites one at a time, beating well after each addition.
4. With mixer on low, beat in half of the flour mixture followed by half of the buttermilk and beat to combine. Add the remaining flour mixture, then the remaining buttermilk and beat until just incorporated.
5. Spread three-quarters of the batter into the prepared pan. Sift the cocoa powder over the remaining batter and add the milk; stir until fully combined.
6. Dollop the chocolate batter over the vanilla batter and carefully spread into an even layer with an offset spatula (don’t swirl them together, just spread the chocolate batter over the vanilla). Sprinkle the drained cherries over the cake batter.
7. Bake 35 to 40 minutes, until a cake tester inserted into the center of the cake comes out clean.
8. Remove cake from the oven and cool completely on a wire rack before adding the frosting.
9. Once the pudding and the cake are both cooled, finish the buttercream. Remove the chilled pudding from the fridge and allow it to come to room temperature.
10. Transfer the room temp pudding to the bowl of a stand mixer fitted with the whisk attachment and beat on medium for several minutes, until it’s very light and creamy.
11. With mixer still on medium speed, add the butter half a tablespoon at a time, stopping mixer to scrape with a rubber spatula every so often.
12. Once the butter is fully incorporated, add the powdered sugar, vanilla, and salt, and beat until smooth. Spread over the fully cooled cake. Refrigerate for 1 hour to set the buttercream before adding the chocolate topping.

Chocolate topping:

1. Place the chocolate in a small heat-proof bowl. Heat the cream in a medium saucepan set over medium heat until it just begins to steam. Pour over the chocolate and allow to sit for 3 minutes.
2. Add the corn syrup, then whisk the chocolate and heavy cream together until the chocolate is melted and mixture is smooth. Allow to cool for 10 minutes.
3. Remove cake from the fridge and spread the chocolate into an even layer over the buttercream. Refrigerate to set the ganache, then serve.

Recipe Notes

• Because this is a complicated cake I strongly suggest that you read through the entire recipe before beginning.  There are step-by-step photos in the post to help you with visuals.
• BE SURE when you make your buttercream that both the pudding and the butter are at room temperature. If the pudding is too hot it will melt the butter; if either is too cold they won't whip together nicely.
• If you don’t want to buy a whole carton of buttermilk for this cake, you can substitute 1 1/3 cups whole milk mixed with 1 tablespoon of lemon juice or white vinegar. Let the mixture sit for 5 minutes before using.
• Store the cake loosely covered with plastic wrap in the fridge for up to 3 days or in the freezer for up to 3 months.

German buttercream adapted from Food 52

Cake adapted from Better Homes and Gardens Baking