Authentic Zwiebelkuchen (German Onion Cake)

This classic Zwiebelkuchen is a real highlight of Germany's autumn. This German onion cake (also known as German onion pie) is made with sour cream, bacon, and of course, onions. When the leaves on the trees start changing color, and the vintners are celebrating their harvest - this onion pie comes to shine.

What is Zwiebelkuchen?

Zwiebelkuchen is a savory onion pie or cake. It is topped with slow-cooked onions, sour cream, and bacon. The base is made from a yeast dough, but you can also find versions made from shortcrust pastry or an oil-quark dough.

You will find this German onion cake either baked in a sheet pan or in a round cake tin. Both versions are common, but the Zwiebelkuchen baked in a cake tin tends to be deeper and moister.

This dish could also remind you of a quiche when baked in a round cake tin. However, the French have their own version of this German Onion Quiche and call it "Tarte à l'oignon". The difference is that the French onion tart does not usually use bacon.

Another similar German dish is Flammkuchen, a flatbread that is also made with onion and bacon - but is a lot drier.

What is the difference between Zwiebelkuchen and Flammkuchen?

Although Zwiebelkuchen and Flammkuchen both have onions and bacon as key ingredients, Zwiebelkuchen has a deeper crust which is more cake or pie-like. Also, you need a lot more onions to make Zwiebelkuchen - the filling is creamier and moister. Flammkuchen is crispier and drier.

Another difference is that on Flammkuchen you add raw onions. Whereas for Zwiebelkuchen you slowly fry the onions to create a moist, sweeter filling.

A common spice for Zwielkuchen is caraway seeds. This helps the digestion of all these onions. This is definitively not a common spice used in Flammkuchen.

History and Origin 

It is unclear who made the "original'' onion cake. It has been mentioned in Southern Germany and the Alsass region since the 19th century. Zwiebelkuchen is a popular autumn dish at wine festivals. The wine-producing areas in Germany include Thuringia, Phalia, Hessia, Franconia, Swabia, Alsass, and the Rhine and Mosel areas. I looked at various recipes, but I can not find significant regional differences in the way they are prepared.

In the German vineyards, it is customary to celebrate a festival once the harvesting season is over and the first wines are ready for drinking. The name of these festivals is "Besen-und Straussenwirstschaften". They are like pop-up wine bars where the vintners sell their wines. This custom originates from the time of the Emperor "Karl the Great" who in the 8^th century allowed the vineyards to keep some of the wine they produced for themselves. [Source: Schmeck den Süden]

What do you call Zwiebelkuchen in English?

Literally translated Zwiebelkuchen means "Onion Cake": "Zwiebel" is the word for onions in German "Kuchen" is the word for cake. However, in America, onion pie would be the more accurate description- as it resembles the American onion and bacon pie.

You pronounce Zwiebelkuchen as an English speaker as "TS-WE-BELL-COOK-EN".

How to make German Onion Cake 

In Germany you call this recipe "Zwiebelkuchen vom Blech" where "vom Blech" means baked on a tray - with which you mean the sheet pan used. This distinguishes it from the Onion Cakes that you bake in a round cake tin.

Ingredients: 

For the yeast base

• 7 g instant yeast (2 teaspoon or 0.24 oz, 1 pouch)
• 180 ml / 5 fl oz lukewarm milk
• ¼ teaspoon salt
• pinch of sugar 
• 300 g / 11 oz flour
• 2 tablespoon vegetable oil

For the onion filling

• 1 kg/ 35 oz onions 
• 200 g / 7 oz bacon (cubed) 
• 1 ground caraway seeds (you can substitute the 2 teaspoon caraway seeds) 
• 400 g/ 14 oz sour cream (you can substitute sour cream with crème fraiche) 
• 3 eggs - medium size
• Salt and pepper to taste

To garnish (optional)

4 tablespoon chopped fresh chives

Zwiebelkuchen Recipe Steps

1. Add the instant yeast and sugar to the lukewarm milk. Mix and leave to rest for 10 minutes. The yeast should activate and you should see little bubbles forming on the surface.
2. Combine the flour and salt in a bowl. Pour in the yeast-milk mixture and oil. Using a stand or hand mixer with a dough hook, knead the dough for about 5 minutes until the dough comes together and pulls away from the sides of the bowl.
3. Lightly grease a large bowl with oil or use nonstick spray. Place the dough in the bowl, turning it to coat all sides in the oil. Cover the bowl with aluminum foil, plastic wrap, or a clean kitchen towel. Allow the dough to rise in a relatively warm environment for 45 minutes.
4. In the meantime, we can start with the onion topping. Peel the onions and chop them into thin rings. Cube the bacon.
5. Heat 1 tablespoon of oil in the frying pan and fry the bacon until crispy. Now add the onions and fry them with the bacon on low to medium heat until translucent. You do not want to hurry this step, as it will add to the sweetness. You don't want the onions to get too brown, they should be more "steamed" than "fried" crispy. Slow-cook the onions for about 10 minutes.
6. Leave the onion mixture to slightly cool.

7. In a separate bowl mix together the sour cream and eggs. Then add the egg-sour cream mix to the onions and bacon and mix well. Season with salt and pepper and caraway seeds to taste. 
8. Preheat the oven to 200°C/ 392°F. Either grease the baking tray with some butter or line it with baking parchment.
9. Once the dough has risen, knead the dough one last time by hand on a floured surface to remove any air bubbles. Then roll it out into a thin rectangle. Lift the dough into the baking form and press the dough into the corners with your finger to create a small rim. 
10. Pour the onion mixture onto the yeast base. Bake in the oven for 35 minutes until it is golden brown. 
11. Leave to cool slightly before serving. To garnish, sprinkle with freshly cut chives (optional).

Recipe Variations:

• Use a different cake tin. Instead of a baking tray use a 10-inch round cake tin.
• Use shop-bought pizza dough or puff pastry as your base. If you need to save time, this is an effective shortcut to take.
• Vegetarian Onion Cake. To make a vegetarian version of this onion cake, just omit the bacon in the recipe. Instead, you can also add in some leeks, to add a different texture or add some grated cheese, such as gouda or cheddar. Another idea is to replace the bacon with smoked tofu.

How to serve Zwiebelkuchen

Serve this German onion pie as a snack with a glass of wine. It also makes a great main course. Pair it with a green salad or a potato salad.

You can eat the slices cold or warm. 

Wine Pairing

Traditionally you will serve this with a young wine called "Federweisser". Federweisser is a young wine that is in the process of turning from grape juice into white wine. The yeast that winemakers to aid fermentation turns sugars into alcohol. This process takes about 2-3 weeks. This is why Federweisser is cloudy. The taste depends on how old the wine is. If it is younger, it will take sweeter and more juice-like, the older it gets the sourer it will be. The alcohol content ranges from 4% to 11%.

A dry white wine (especially Riesling) also goes well with this savory tart.

Prepare ahead

Zwiebelkuchen tastes best the day you cook it. However, you can prepare the yeast dough a day ahead. Either for the first or second rise, you can store it in the fridge. Ensure that you let the dough get back to room temperature before filling it, as otherwise it will not back properly.

Storage Instructions 

Store any leftover onion cake in an airtight container in the fridge. Consume within three days.

Freezer

Divide it into portions and place it in an airtight container. It can stay frozen for up to three months. Defrost at room temperature. If you like to eat it warm, place it in the oven for 5 minutes to crisp up.