German onion tart is the cozy, savory bake that shows up all over southwest Germany every fall, right around the grape harvest. Known at home as Zwiebelkuchen, it’s a thin yeast crust covered in a deep layer of soft onions, smoky bacon and a creamy egg custard, finished with a golden blanket of melted cheese.
This version keeps things simple. The dough comes together in one bowl with no fussy kneading schedule, the filling is cooked in a single pan, and the whole tart bakes on one sheet. This German onion tart feeds a crowd, travels well to potlucks, and it tastes just as good warm as it does at room temperature the next day.
Quick answer: To make German onion tart, knead 450 g (3 2/3 cups) flour with dry yeast, salt, sugar, cold water and soft butter, rest the dough 30 minutes, then roll it out on a baking sheet. Brown 800 g (1 3/4 lb) sliced onions and 200 g (7 oz) diced bacon in butter and oil, stir in 3 eggs whisked with 200 ml cream, salt, pepper and nutmeg, spread over the dough, top with 250 g (9 oz) grated cheese and bake at 200°C (390°F) for about 30 minutes.
Why You’ll Love This German Onion Tart
- Simple pantry ingredients. Onions, bacon, eggs, cream, cheese and a basic yeast dough. Nothing hard to find.
- One sheet feeds many. A full baking sheet cuts into about 12 generous squares, perfect for a gathering or a week of lunches.
- Sweet, smoky and creamy. Slowly softened onions turn mellow and sweet, the bacon adds salt and smoke, and the custard ties it all together.
- Great hot or cold. Serve it straight from the oven or pack leftover slices for the next day.
Ingredients You’ll Need
For the dough you’ll need all-purpose flour, one packet of dry yeast, a pinch each of salt and sugar, cold water and softened butter, plus a little extra flour for rolling.
For the topping you’ll need yellow onions, bacon (a smoky slab bacon you can dice works best), a spoonful each of oil and butter, eggs, heavy cream, grated cheese, salt, pepper and nutmeg. A mild melting cheese such as Emmental, Gouda or a Swiss-style cheese suits the onions well. The exact amounts are in the recipe card below.
How to Make German Onion Tart
Making a German onion tart takes about an hour from start to finish, and most of that is resting and baking time.
1. Make the dough. Put the flour, yeast, sugar and salt in a large bowl and press a well into the middle. Pour in the cold water, add the soft butter and knead everything into a smooth dough. Let it rest for about 30 minutes.
2. Roll it out. Roll the dough out on a floured surface to the size of your baking sheet. Lay it on the sheet and press the edges up a little so the filling stays put.
3. Mix the custard. Blend the eggs and cream with an immersion blender until smooth, then season with salt, pepper and nutmeg.
4. Cook the onions and bacon. Peel the onions, halve them and slice them into strips. Dice the bacon. Cook both in a large pan with the butter and oil until they take on some color. Take the pan off the heat, stir in the egg mixture, taste and adjust the seasoning if needed.
5. Top and bake. Spread the filling over the dough, scatter the cheese on top and bake in a preheated oven at 200°C (390°F) with top and bottom heat for about 30 minutes, until the cheese is golden and the custard is set.
Tips for the Best Onion Tart
- Slice the onions evenly. Strips of a similar width soften at the same speed, so none stay crunchy.
- Take your time with the browning. A little color on the onions and bacon means much deeper flavor in the finished tart.
- Let the pan cool slightly. Stirring the custard into a very hot pan can scramble the eggs, so pull it off the heat first.
- Check the center. The custard should be set and no longer wobbly in the middle. Egg dishes are safe when they reach 160°F (71°C), as listed in the FoodSafety.gov temperature chart.
- Rest before slicing. Ten minutes on the counter lets the German onion tart firm up, so clean squares are much easier to cut.
- Using a fan oven? Lower the temperature by about 20°C (35°F) and keep an eye on the cheese.
What to Serve with German Onion Tart
A well-chilled glass of dry white wine is the classic match, or try sparkling apple cider for an alcohol-free option. A crisp green salad, especially lamb’s lettuce with a simple vinaigrette, cuts through the richness nicely. For a bigger German spread, add a plate of crispy German potato pancakes, or browse more hearty mains in our dinner recipes.
German Onion Tart FAQ
What is Zwiebelkuchen?
Zwiebelkuchen means “onion cake” in German. It’s a savory tart of onions, bacon and an egg-and-cream custard on a yeast or shortcrust base, popular in the wine regions of southwest Germany during the fall harvest.
Can I make German onion tart ahead of time?
Yes. Bake it, let it cool, then cover and refrigerate for up to 3 days. Reheat squares in a 175°C (350°F) oven for about 10 minutes to crisp the crust again.
Can I freeze it?
Baked and cooled slices of German onion tart freeze well for up to 2 months. Wrap them tightly, thaw in the fridge overnight and reheat in the oven.
Can I make it without bacon?
You can leave the bacon out for a vegetarian version. Add a little extra salt and a pinch of caraway or smoked paprika to make up for the missing smoky flavor.
What size baking sheet do I need?
A standard oven baking sheet with a low rim is ideal. In US terms, a half sheet pan of about 18 x 13 inches (46 x 33 cm) works well.
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