Classic French Onion Soup with Gruyère Toasts (Cozy Winter Favorite)

This cozy French onion soup layers deeply caramelized onions, beefy broth, and bubbling Gruyère-topped toasts for a restaurant-worthy comfort meal at home. Ready to warm you from the inside out, it’s the ultimate winter recipe that brings the flavor without fuss.

I first made this for my husband on a snowy December evening when we had nothing in the fridge but onions, broth, and leftover baguette. That night turned into a tradition , every first snow, we pull out the big red pot and make a batch together.

Prep Time: 20 minutes . Cook Time: 1 hour 15 minutes . Total Time: 1 hour 35 minutes

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Here’s What You’ll Need

• 6 large red or yellow onions (about 3 pounds), thinly sliced
• 4 tbsp extra virgin olive oil
• 2 tbsp butter
• 1 tsp sugar
• Kosher salt
• 2 cloves garlic, minced
• 8 cups beef stock, chicken stock, or both
• 1/2 cup dry vermouth or dry white wine
• 2 bay leaves
• 1 tbsp fresh thyme leaves or 1/2 tsp dried thyme
• 1/2 tsp freshly ground black pepper
• 2 tbsp brandy (optional)
• 8 slices (1-inch thick) French bread or baguette
• 1 1/2 cups grated Gruyère cheese
• Grated Parmesan cheese (for sprinkling)

Step-by-Step Cooking Guide

1. Slice the onions: Cut onions root to stem into thin slices. You should have about 10 cups.
2. Start caramelizing: In a large pot, heat 3 tbsp olive oil over medium. Add onions and stir to coat. Cook 15–20 min, stirring often.
3. Deepen the color: Add the last tbsp olive oil and butter. Raise heat to med-high. Stir frequently for 20–40 min until onions turn golden brown.
4. Sweeten + garlic: Sprinkle sugar, 1 tsp salt, and cook 10–15 more minutes until deeply browned. Stir in minced garlic and cook 1 minute.
5. Deglaze: Pour in wine/vermouth, scraping up the browned bits.
6. Simmer: Add stock, bay leaves, thyme. Bring to a simmer, cover, and reduce heat. Simmer gently 30 minutes.
7. Final touches: Season with pepper, more salt if needed. Stir in brandy (optional). Discard bay leaves.
8. Make cheesy toasts: While soup simmers, toast oiled bread slices at 450°F until golden (5–7 min). Flip, top with cheeses, and return to oven until bubbly.
9. Serve: Ladle soup into bowls and top with a cheese toast. Or broil all together in oven-safe bowls for that bubbling finish.

Betty’s Best Tips

• Use a mix of yellow + red onions for more depth.
• Gruyère is traditional, but Fontina or Swiss work in a pinch.
• Deglazing with wine adds rich flavor, but broth alone still delivers.

Nutrition Breakdown (Per Serving)

• 375 calories
• 16g fat
• 39g carbs
• 17g protein

Make It Yours

• Try sourdough or rye bread for a twist.
• Add a splash of Worcestershire for umami depth.
• Serve with a green salad and glass of dry red.

Leftovers & Storage

• Soup keeps in the fridge 4 days; reheat gently.
• Freeze without bread/cheese for up to 3 months.
• Toast bread and melt cheese fresh for serving.

What I Learned the Hard Way

The first time I made this, I rushed the onions. Big mistake. They need time. Once I slowed down, the flavor deepened tenfold. Don’t skip the full caramelization , it’s the soul of the soup.

Curious Cook Q&A

Q: Can I make this vegetarian?
A: Yes! Use veggie stock and skip the brandy.

Q: What cheese substitutes work best?
A: Swiss or provolone are great melty options.

Let’s Make Soup Memories Tag me @FlavorsByBetty if you make this! I LOVE seeing your cozy bowls