Caramelized Onion Sourdough Bread with Jarlsberg

Caramelized onion sourdough is what happens when you take a loaf you already know how to bake and load it with something worth waiting for. We brown a pound and a half of onions down until they’re sweet and jammy, fold them through the dough along with diced Jarlsberg, and let the whole thing ferment slowly overnight. It makes two savory loaves that eat like a meal on their own — thick slices, good butter, nothing else needed.

Caramelized Onion Sourdough Bread with Jarlsberg

A crusty caramelized onion sourdough loaf folded with nutty Jarlsberg — naturally leavened with sifted landhvete and emmer.

Print Recipe Pin Recipe

Prep Time 1 hour hr 15 minutes mins

Cook Time 35 minutes mins

Fermenting & proofing 20 hours hrs

Total Time 21 hours hrs 50 minutes mins

Servings: 2 loaves

Course: Bread, Side Dish

Cuisine: Nordic, Scandinavian

Ingredients Equipment Method Notes

Ingredients

  

Browned onions (make first — they must be cold)

• 3 large yellow onions about 720 g / 1.6 lb, thinly sliced
• 3 tbsp neutral oil enough to coat the pan

Dough

• 140 g active sourdough starter about ⅔ cup — bubbly, ripe and passing the float test
• 400 g water about 1⅔ cups, lukewarm
• 350 g sifted landhvete flour about 2¾ cups plus 2 tbsp — or bread flour
• 250 g sifted emmer flour about 2 cups — or sifted spelt
• 15 g fine sea salt about 2½ tsp

Folded in

• 240 g Jarlsberg about 1¾ cups, cut in ¼ in / ½ cm dice
• the cooled browned onions roughly 230 g / 1 cup once reduced

For the baskets

• 25 g rice flour for dusting the linen cloths; it doesn't absorb, so the loaves release cleanly

Equipment

• Digital kitchen scale This dough runs on weight, not volume — 67% hydration leaves no room for guessing.
• Heavy skillet or cast iron pan You need a wide, heavy base to brown 1.6 lb of onion without steaming it.
• 2 Banneton proofing baskets, 8 in Hold the shape through the cold retard and leave the spiral pattern. Dust with rice flour. If you only have one, proof the second loaf in a cloth-lined bowl.
• 2 Linen proofing cloths Line the bannetons — rice flour plus linen is the combination that releases cleanly with heavy inclusions.
• Bench scraper Essential here. A dough loaded with cheese and onion sticks, and hands alone will tear it.
• Bread lame One deep, confident cut. A loaf this heavy needs a sharp blade — diced cheese near the surface will drag a dull one.
• Metal roasting tray Sits on the rack below and takes the water for steam. Never glass — it will shatter.
• Wire cooling rack This loaf needs a full cool before slicing or the melted cheese smears.

Method

 

1. Brown the onions (day before, or the morning you mix)

Slice the onions thin and add them to a heavy skillet with the oil over medium-low heat. No salt here — the dough and the cheese bring plenty.

1. Cook 45–60 minutes, stirring every few minutes. They will release water, collapse, then slowly turn deep amber and jammy. Don't rush this with high heat — you want sweet and soft, not scorched and bitter. 720 g raw cooks down to roughly 230 g.
2. Cool completely. Spread them on a plate and refrigerate if needed. Warm onions will slack the dough and throw off your fermentation — this matters more than it sounds.

Day 1 — mix and ferment

1. Feed your starter the morning you bake so it's lively when you mix.
2. Mix the dough. Whisk the starter into the lukewarm water to loosen it, then add both flours and mix by hand until no dry flour remains. Hold the salt back. Cover and rest 1 hour.
3. Add the salt. Sprinkle it over and squeeze and fold it through until fully worked in. The dough tightens slightly.
4. Stretch and fold — every 30 minutes, 4 sets. Wet hand, grab one side, stretch up, fold over the center, quarter turn, repeat around. Over these 2 hours the dough goes from shaggy to smooth and elastic.
5. Fold in the onions and cheese on the last set. Spread the dough out, scatter the cold onions and the 240 g of diced Jarlsberg across it, then fold it up and over itself until they're evenly distributed. Work gently — the gluten is already built and you don't want to tear it.
6. Bulk ferment until risen 30–50%. Roughly 4–6 hours total from mixing, depending on your kitchen. The dough should look domed and jiggly with bubbles along the sides. Watch the dough, not the clock.
7. Divide in two. Tip the dough onto a lightly floured surface and cut it into two equal pieces, about 810 g each. Round each one loosely into a ball.
8. Bench rest 20–30 minutes, uncovered. Don't skip this — the dough needs to relax before final shaping or it will fight you and tear.
9. Shape each piece into a taut round, pulling it toward you against the counter a few times to build surface tension.
10. Into the bannetons, seam-side up, in linen cloths dusted generously with rice flour.
11. Cold retard 12–16 hours in the fridge. The cold firms the dough so it scores cleanly and springs high, and it deepens the flavor.

Day 2 — bake

1. Preheat hard. 45–60 minutes ahead, put the perforated baking tray on the middle rack and the metal roasting tray on the rack below, and heat the oven to 250°C / 480°F.
2. Score the cold loaves. Turn them out, dust off the excess flour and make one confident deep cut down the length of each with the lame.
3. Bake with steam, 20 minutes. Slide both loaves onto the hot tray, pour a cup of boiling water into the roasting tray below and close the door fast.
4. Drop to 200°C / 390°F, remove the steam tray, and bake 15 minutes more until the crust is deep brown and the cheese at the surface has caramelized.
5. Cool completely on a wire rack — at least 2 hours. Slicing warm drags the melted cheese through the crumb.

Notes

Chef’s tip — cold onions, added late. Two things decide whether this loaf works. The onions go in cold, because warm onions soften the gluten and push fermentation unevenly. And the inclusions go in on the last fold, not the first — nearly 500 g of onion and cheese against 600 g of flour will tear a gluten network that hasn’t been built yet. Build the dough first, then load it.

Two loaves, not one. We divide this dough rather than baking one large boule. Smaller loaves bake through more evenly with this much inclusion, and you get twice as much crust — which is where the browned onion and caramelized cheese live. Temperatures and times stay exactly the same.

No salt on the onions. The dough already carries 2.5% salt, and 240 g of Jarlsberg brings a good deal of its own. Salting the onions on top of that tips the whole loaf over. Onions and oil, nothing else.

Any firm cheese works. The 240 g of Jarlsberg gives the sweet, nutty note that suits browned onion, but Gruyère, Emmental, Comté or a sharp cheddar are all excellent here. Keep the weight the same and cut it into ¼-inch dice — shreds melt out and disappear into the crumb.

About the flours. Landhvete and emmer are both heritage wheats — sifted, so not quite whole grain. Outside Scandinavia, bread flour stands in for the landhvete, and sifted spelt for the emmer. Emmer flour is worth seeking out from a specialty mill if you can; it brings a mild sweetness that plain wheat doesn’t.

 

What makes this caramelized onion sourdough work

The dough itself is nothing new — it’s the same base we use for our beginner sourdough and our baguettes: 600 g flour, 400 g water, a ripe starter and salt. What changes everything is what goes into it, and when.

Nearly 500 g of onion and cheese against 600 g of flour is a heavy load. Add that early and you’ll shred a gluten network that hasn’t finished building. So we do all four sets of stretch and folds first, get the dough smooth and elastic, and only then spread it out and scatter the onions and cheese across it.

We also leave the onions unsalted. Between the 2.5% salt in the dough and 240 g of Jarlsberg, this loaf already has all the salt it needs — season the onions as well and you’ll taste it.

And the onions go in cold. Straight from the pan they’ll slack the dough and speed up fermentation in patches. Brown them the day before if that’s easier — the flavor is better for the wait anyway.

We divide the dough in two. A single 1.6 kg boule carrying this much onion and cheese is a lot to bake through evenly. Two smaller loaves handle better on the bench, bake more reliably, and give you twice the crust — which with browned onion and melted cheese on the surface is where a good share of the flavor sits. Same oven temperature, same 35 minutes.

What to expect when you cut it

A few things will look like mistakes the first time. They aren’t.

The crumb sits tighter than a plain loaf. That much inclusion interrupts the gluten structure, so this bakes up softer and closer rather than wide open. That’s the trade for the flavor, and it’s the right result — don’t chase an open crumb here.

Cheese near the crust melts out and caramelizes. You’ll get crisp, savory patches where it has run onto the surface and browned. It’s the best bite in the loaf.

Any onion left on the outside goes dark. Pieces that poke through the crust catch more heat and colour up almost black in places. There’s nothing wrong with that — it just tastes a little different there, deeper and more roasted, and it’s part of what gives this loaf its look.

Make it your own

Jarlsberg is the obvious choice for us, and its sweet, nutty edge is a natural match for browned onion. But any firm cheese that melts well will work: Gruyère and Comté push it richer and more savory, Emmental stays close to the Jarlsberg character, and a sharp cheddar gives it a tangier bite. Keep the weight the same at 240 g and cut it small — ¼ inch dice distributes far better than shreds.

A handful of chopped thyme or a grind of black pepper folded in with the cheese is worth trying if you want a third note.

More Nordic bakes you’ll love

Sourdough Baguettes — same dough, different shape
Beginner Sourdough Bread (Your First Loaf)— the same base dough, without the inclusions
Whole Grain Sourdough Bread — the everyday loaf to move on to