There’s something deeply comforting about slowly caramelized onions in butter, isn’t there? That sweet, earthy smell wafting through the house — it’s the kind of scent that makes you pause, close your eyes, and just breathe. If soup could hug you, this would be it.
I first made this on a Sunday afternoon with music playing low and slippers on. The onions took their time, the broth bubbled gently, and I had just enough cheese left to turn it into the kind of meal you feel proud of with very little effort. Best part? You can pretend you’re in a rustic Parisian café while you’re really just in your dressing gown.
Why You’ll Love It
- Feels fancy, tastes comforting — ideal date night or solo treat.
- Budget-friendly with big flavor pay-off.
- That cheesy, melty lid? It’s half the reason we’re here.
- You don’t need loads of gear — one pot, one grill.
- Great way to use up that bag of onions sitting in the back of the cupboard.
Ingredients
- ½ cup unsalted butter
- 2 tbsp olive oil
- 4 cups sliced onions (about 4 large ones)
- 5 cups beef broth (go for rich and good-quality if you can)
- 2 tbsp dry sherry (optional but really good)
- 1 tsp dried thyme
- Salt & pepper, to taste
- 4 slices French bread, slightly stale is fine
- 4 slices provolone cheese
- 2 slices Swiss cheese, diced
- ¼ cup grated Parmesan
How to Make It
Get the dry bits sorted
Slice those onions thinly. Don’t cry too much — it’s part of the ritual.
Sort the wet
In a big pot (think soup-for-a-crowd big), melt your butter with the olive oil over medium heat.
Make the base
Chuck in the onions and stir them gently for a good 25–30 minutes. Don’t rush this. You want them soft and golden, not brown or crispy.
Build the broth
Once the onions are lovely and jammy, pour in the beef broth, add the thyme, the sherry (if using), salt and pepper. Let it all simmer away for 30 minutes while you preheat your oven’s grill.
Shape your topping
Lay your bread slices out and get your cheese ready — provolone, diced Swiss, and a sprinkle of Parmesan. Mix and match as you like.
Wrap and steam
Not exactly wrapping and steaming, but this is where it gets cozy. Ladle the soup into oven-safe bowls. Top each with bread and that glorious pile of cheese.
Cool and unwrap
Place the bowls on a baking tray and broil for 2–3 minutes until the cheese melts, bubbles, and starts to brown around the edges.
Finish it off
Take a breath. Let it sit for a minute or two so you don’t scorch your tongue. Then dive in. It’s soup, but it’s also dinner.
Common Mistakes and How to Dodge Them
My onions burnt. What went wrong?
Heat was too high. Keep it low and slow — caramelized, not crisped.
Soup feels bland.
Try a splash more sherry or an extra grind of black pepper. Salt might be off if your broth was low-sodium.
Bread’s soggy and sad.
Toast it first, or use crusty bread. A bit of crunch under the cheese works wonders.
Cheese slid off the top.
Make sure the bread fits the bowl and don’t stack cheese too high — melt it just enough to cling.
It’s too salty.
Between broth and cheese, it adds up. Taste as you go. Easy to fix with a splash of water or unsalted stock.
Storage and Reheating
Fridge:
Soup (without bread/cheese) lasts up to 3 days in a sealed container.
Freezer:
Freeze the soup base only — no cheese or bread. It keeps for 2–3 months. Defrost in the fridge overnight.
Microwave:
Reheat soup on medium, stirring halfway. Cheese-topped bowls don’t reheat well here.
Oven:
Best for a full reheat. Ladle soup into ovenproof bowls, add bread and cheese, bake at 180°C (350°F) until bubbling.
Frequently Asked Questions
Can I use vegetable broth instead of beef?
You can, but it won’t have that same deep richness. Add a bit of soy sauce or mushroom stock for depth.
No sherry — what else can I use?
White wine, dry vermouth, or even a splash of balsamic vinegar in a pinch.
Is it okay to skip the cheese?
Sure, but the cheese is kind of the point. Try a vegan cheese or skip the topping and serve with cheesy toast on the side.
What kind of onions are best?
Sweet ones like Vidalia or Walla Walla caramelize beautifully. But regular yellow onions work fine too.
Nutrition Facts (Per Serving)
- Calories: 586
- Fat: 44g
- Carbs: 28g
- Protein: 21g
- Sodium: 1592mg
- Sugar: 5g
Try More Mary Berry Recipes:
Mary Berry French Onion Soup
Description
A cozy, classic French Onion Soup with buttery slow-cooked onions, rich broth, and bubbling cheesy bread on top.
Ingredients
Instructions
- Melt butter and olive oil in a big pot over medium heat. Add onions and cook slowly for 25–30 minutes until soft and golden.
- Add broth, thyme, sherry, salt, and pepper. Simmer gently for 30 minutes.
- Preheat the grill. Toast bread slices if you like extra crunch.
- Ladle soup into ovenproof bowls. Top each with bread, provolone, diced Swiss, and Parmesan.
- Broil for 2–3 minutes until the cheese is bubbling and golden brown.
Notes
- Toast bread before broiling to avoid soggy bottoms.
- Use Gruyère if Swiss isn’t available — it melts beautifully.
- Be mindful of salt — cheese and broth can be salty on their own.
- Avoid rushing the onion caramelization. That’s where all the magic happens.