There’s something truly magical about the moment onions hit a warm pan and start to soften, sizzle, and slowly transform into sweet, golden goodness. This Caramelized Onion & Thyme Soup is my ultimate comfort-in-a-bowl—a little rustic, totally fancy-feeling, and bursting with cozy depth. Whether you’re curled up with a blanket or setting the table for friends, this soup brings all the slow-simmered love with very little stress.
Why You’ll Love This Recipe
One chilly afternoon, I whipped this up as a last-minute dinner idea—and my family fell for it faster than the cheese melted on the crouton topping. Now it’s in our regular rotation. Trust me, those caramelized onions are pure magic!
- Deep, rich flavor from slow-cooked onions and fragrant thyme
- Easy to make ahead—and even better the next day
- Customizable for meat-eaters, vegetarians, and vegans alike
- That cheesy crouton topping? Game. Changer.
Ingredients Breakdown
Essentials
- 4–5 large yellow onions, thinly sliced (about 2–2.5 pounds)
- 2 tablespoons unsalted butter (or 1 tablespoon butter + 1 tablespoon olive oil)
- 1 tablespoon olive oil
- 1/2 teaspoon salt, plus more to taste
- 1 teaspoon sugar (optional, helps with caramelization)
- 1/2 cup dry white wine or vermouth (optional, for deglazing)
- 4 cups vegetable or chicken stock
- 2–3 sprigs fresh thyme or 1 teaspoon dried thyme
- 1/4 cup heavy cream or crème fraîche (optional)
- Black pepper, to taste
- 4–6 slices crusty bread (optional topping)
- 1 cup grated Gruyere or Swiss cheese (or vegan alternative)
Pro Tips
- Use a mix of butter and oil for rich flavor and golden browning
- Go low and slow—caramelizing onions properly takes time, but results are worth it
- Deglazing lifts all the flavor-packed bits from the pan—don’t skip it
- Fresh thyme gives brighter aromatics, but dried works in a pinch
- A splash of balsamic vinegar or lemon juice at the end can balance the richness
Step-by-Step Instructions
- In a large, heavy-bottomed pot, melt the butter with the olive oil over medium-low heat.
- Add the sliced onions and 1/2 teaspoon salt. Stir to coat the onions gently.
- Cook slowly, stirring every few minutes, for 15–20 minutes until onions are soft and translucent.
- Sprinkle in the sugar (if using), then continue cooking another 25–40 minutes, stirring regularly, until the onions are deep golden brown and caramelized. Adjust heat if needed to avoid burning. Add a splash of water if bits start sticking too much.
- If using wine or vermouth, pour it in now. Scrape the bottom of the pan and let it cook for 2–3 minutes until mostly evaporated.
- Add thyme and pour in the stock. Bring to a gentle simmer and cook uncovered for 15–25 minutes to let flavors meld. Remove thyme sprigs before blending or serving.
- (Optional) For a smoother texture, blend with an immersion blender or regular blender—fully or partially depending on your preference.
- Stir in the cream (if using) and season with salt and pepper to taste. Add a splash of lemon juice or vinegar to brighten, if desired.
- To make the cheesy crouton topping: brush bread slices with olive oil and bake at 400°F for 5–7 minutes per side until golden and crisp. Rub with garlic if you’d like, then top with grated cheese and pop under the broiler until bubbly and golden, 1–3 minutes.
- Ladle soup into bowls, top with a cheesy crouton or drizzle of olive oil and a few thyme leaves. Serve warm and smile.
Chef’s Tips and Tricks
- Caramelized onions freeze beautifully! Make a double batch and freeze half for next time.
- Keep your heat low and your patience high—don’t rush the caramelizing step.
- Add mushrooms or shredded chicken at the simmer stage for extra heartiness.
- Want more depth? A teaspoon of miso paste stirred in takes the umami next-level.
- Fresh bread is lovely, but slightly stale bread toasts up like a dream!
Recipe Variations and Serving Suggestions
- Vegan version: Use olive oil, veggie broth, and skip the dairy or use plant-based cream/cheese.
- Gluten-free: Skip the bread or use GF baguettes—don’t forget the broiled cheese topping!
- Spiced up: Add a pinch of smoked paprika or even a dash of chili flakes for warmth.
- Simple lunch: Serve with arugula tossed in lemon vinaigrette and a slice of baguette.
- Dinner party starter: Serve in mini mugs with mini croutons to impress your guests.
FAQs
Can I make this ahead of time?
Absolutely! The flavors only get better. Make a day ahead, store in the fridge, and reheat gently on the stove.
Can I freeze the soup?
Yes. Let it cool completely, transfer to airtight containers, and freeze for up to 3 months. Thaw overnight in the fridge before reheating.
Why are my onions not browning?
Patience and low heat are key. Make sure you’re not crowding the pan and avoid high heat—you want slow caramelization, not quick frying.
Recipe Card
Prep Time: 15 minutes
Cook Time: 90 minutes
Total Time: About 1 hour 45 minutes
Ingredients:
- 4–5 large yellow onions, sliced
- 2 tbsp butter + 1 tbsp olive oil
- 1/2 tsp salt, more to taste
- 1 tsp sugar (optional)
- 1/2 cup dry white wine or vermouth (optional)
- 4 cups vegetable or chicken stock
- 2–3 sprigs thyme or 1 tsp dried thyme
- 1/4 cup cream or crème fraîche (optional)
- Black pepper, to taste
- Crusty bread + grated Gruyere for topping (optional)
Instructions:
- Caramelize onions low and slow with butter, oil, and salt until bronze and sweet—about 45–60 minutes total.
- Add wine or vermouth, simmer until evaporated. Add stock and thyme. Simmer 20 minutes.
- Remove thyme sprigs, blend if desired, then stir in cream and season. Toast bread, top with cheese, and broil until golden.
- Serve soup hot with a cheesy crouton or fresh thyme drizzle.
Nutrition: ~275 calories per serving
If you try this cozy soup, I’d love to hear how it turned out! Leave a comment below, share your delicious creation on Instagram, and tag me @thekitchensaid. It always makes my day to see your kitchen magic!
