Sheet-pan focaccia with caramelized allium topping
French Onion & Gruyère Focaccia (French-Inspired)
Slow-caramelized onions, melted Gruyère and thyme over a pillowy focaccia — the sweet-savoury aroma of French onion soup in a sheet-pan bread.
- Total
- 5 hr
- Hands-on
- 55 min
- Hydration
- 72%
- Skill
- intermediate
By FocacciaRecipe editorial · Updated 2026-07-05 · In editorial development; independent bake-test pending
The short version
Caramelize 500 g sliced onions slowly (35–45 minutes) and cool them, then spread over a dimpled 72% hydration focaccia, scatter grated Gruyère, and bake at 230°C/450°F for 20–24 minutes until the cheese is molten and the edges are deep gold.
Why this works
Caramelizing the onions in advance drives off their water and concentrates their sugars, so they season the bread instead of steaming it soggy; Gruyère melts cleanly and browns without splitting; a standard 72% focaccia dough stays tall and airy under the topping.
The schedule
~1.1h hands-on of 4.7h total · same day
- Mix & fold · 1.1h
- Bulk ferment · 2h
- Proof · 1h
- Bake · 22m
- Cool · 15m
Terracotta is active work; olive is unattended rising; red is the bake.
Ingredients
Method
- 1
Caramelize the onions (make ahead)
Melt butter with oil over medium-low heat, add onions and the 1/2 tsp salt, and cook, stirring often, 35–45 minutes until jammy and deep amber. Deglaze with sherry near the end and let it cook away. Cool completely.
Look for: The onions should be soft, glossy and mahogany — no visible liquid pooling. If they look wet, keep cooking.
Avoid: Do not rush on high heat — scorched onions turn bitter. Cool them fully before topping so they do not slacken the dough.
- 2
Mix the dough
Whisk flour and yeast, add water and 15 g of the oil, then the salt. Mix to a shaggy, sticky dough with no dry flour.
Look for: Wet and tacky but cohesive; it will smooth out during folds.
- 3
Bulk ferment with folds
Do 2–3 stretch-and-folds over the first 90 minutes, then rest until nearly doubled and bubbly.
Look for: Domed, jiggly and full of bubbles under the surface.
- 4
Pan and proof
Oil the sheet pan with the remaining oil, transfer the dough, and gently stretch toward the edges. Proof until puffy, about 1 hour.
Look for: Dough relaxes to fill the pan and jiggles when nudged.
- 5
Dimple, top and bake
Dimple the dough all over with oiled fingers. Spread the cooled onions evenly, scatter the Gruyère and thyme, and grind over pepper. Bake at 230°C/450°F for 20–24 minutes.
Look for: Cheese is molten and freckled brown; edges are deep gold and the base is crisp when you lift a corner.
- 6
Finish and cool
Slide onto a rack, sprinkle flaky salt, and cool 10–15 minutes before cutting.
Look for: A short rest lets the crumb set so the cheesy top slices neatly.
What good looks like
- Crumb: Open and airy, enriched where the onion juices soak in.
- Crust: Crisp oiled base; tender edges.
- Height: About 3 cm tall.
- Color: Deep gold with molten, freckled Gruyère.
If something went wrong
| Symptom | Likely cause | Fix |
|---|---|---|
| Soggy, pale top | Onions added warm or under-caramelized (still watery) | Cook onions until no liquid pools and cool them fully before topping. |
| Cheese greasy or split | Oven too hot or bake too long | Hold at 230°C/450°F and pull as soon as the Gruyère is molten and just browning. |
| Bitter onion flavor | Onions scorched over high heat | Caramelize low and slow; stir often and deglaze if they catch. |
Storing & reheating
Storage: Keep covered at room temperature 1 day, or refrigerate up to 3 days.
Freezing: Freeze cooled pieces up to 1 month, wrapped well.
Reheating: Re-crisp in a 200°C/400°F oven 5–7 minutes to re-melt the cheese; avoid the microwave.
Contains wheat/gluten and dairy (butter, Gruyère).
Tools & ingredients for this focaccia
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Core pantry
- Bread flour (opens Amazon) ↗ — High-protein bread flour or Italian “00” both work.
- Fine sea salt (opens Amazon) ↗ — Fine sea salt for the dough.
- Instant yeast (opens Amazon) ↗ — Instant (or active dry) yeast keeps for months.
- Extra-virgin olive oil (opens Amazon) ↗ — Use a good EVOO you like the taste of.
- Flaky finishing salt (opens Amazon) ↗ — For the crunchy finish.
Fresh — buy local
- Onions (opens Amazon) ↗ — A kitchen staple; buy fresh.
- Dry sherry or dry white wine (opens Amazon) ↗ — A common item; buy fresh or from your pantry.
- Cheese (opens Amazon) ↗ — Buy fresh from a good cheese counter or deli.
- Fresh herbs (opens Amazon) ↗ — Fresh is best; a windowsill pot works well.
- Fresh vegetables (opens Amazon) ↗ — Buy fresh and in season.
You don’t need to buy everything here — many items are already in most kitchens. Fresh produce, cheese and herbs are best bought local and in season.
Frequently asked
- Can I make this like an onion tart instead?
- This is a thick focaccia, not a tart or pissaladière — the onions top a tall, airy bread rather than a thin pastry base.
- Can I caramelize the onions the day before?
- Yes, and it is recommended. Store them covered in the fridge and bring to cool room temperature before topping.
Keep baking
In these collections
Source: https://www.focacciarecipe.com/recipes/french-onion-gruyere-focaccia · © 2026 FocacciaRecipe.com
In editorial development — this recipe has not yet completed physical bake-testing.