French Onion Soup
Experience bistro elegance with this classic French onion soup featuring deeply caramelized onions in rich beef broth, topped with crusty bread and bubbling Gruyère cheese. This timeless favorite transforms simple ingredients into pure comfort through patience and technique.
Prep Time 15 minutes mins
Cook Time 1 hour hr 15 minutes mins
Total Time 1 hour hr 30 minutes mins
Course Appetizer, Soup
Cuisine French
Large heavy-bottomed pot or Dutch oven
6 oven-safe soup bowls or crocks
For the Soup
- 4 tbsp unsalted butter
- 2 tbsp olive oil
- 4 lb yellow onions thinly sliced (about 8 large onions)
- 1 tsp granulated sugar
- 4 piece garlic cloves minced
- 1/2 cup dry white wine or sherry
- 8 cup beef broth high quality
- 2 piece bay leaves
- 4 piece fresh thyme sprigs or 1 tsp dried
- 1 tbsp Worcestershire sauce
- salt and black pepper to taste
For the Topping
- 1 piece French baguette sliced 1-inch thick
- 2 tbsp butter melted, for brushing
- 2 cup Gruyère cheese shredded
- 1/2 cup Parmesan cheese grated
Caramelize onions: In a large heavy-bottomed pot or Dutch oven, melt butter with olive oil over medium heat. Add sliced onions and sugar. Cook, stirring every 5 minutes, for 45-50 minutes until onions are deep golden brown and caramelized. Don't rush this step - it's the foundation of flavor. If onions start to stick, add a splash of water and scrape up browned bits.
Add aromatics: Stir in minced garlic and cook for 1-2 minutes until fragrant. Pour in white wine, scraping up any browned bits from bottom of pot. Let wine reduce by half, about 3-4 minutes.
Build the soup: Add beef broth, bay leaves, thyme sprigs, and Worcestershire sauce. Bring to a boil, then reduce heat and simmer uncovered for 20-30 minutes to allow flavors to meld. Season with salt and pepper to taste. Remove bay leaves and thyme stems.
Prepare bread: While soup simmers, preheat oven to 400°F. Arrange baguette slices on baking sheet. Brush both sides with melted butter. Toast in oven for 5-7 minutes, flipping once, until golden and crispy. Set aside.
Assemble bowls: Preheat broiler. Ladle hot soup into oven-safe bowls or crocks, filling about 3/4 full. Place 1-2 toasted bread slices on top of each bowl. Generously cover with shredded Gruyère and grated Parmesan cheese, making sure bread is completely covered.
Broil and serve: Place bowls on a baking sheet for easy handling. Broil 2-3 minutes until cheese is melted, bubbling, and golden brown on top. Watch carefully to prevent burning. Let cool for 2-3 minutes before serving - soup will be extremely hot. Serve immediately.
Patience is key for proper caramelization - rushing produces pale onions without deep flavor. Use a mix of beef and chicken broth for lighter version. Gruyère is traditional but Swiss cheese works well. Yellow onions caramelize better than white or red. Make soup base 2-3 days ahead; flavor improves with time. Add bread and cheese just before serving. Freeze soup base (without bread and cheese) for up to 3 months. For vegetarian version, use vegetable broth and skip Worcestershire or use vegetarian version.
ALLERGEN INFORMATION: Contains dairy (butter, Gruyère cheese, Parmesan cheese) and gluten (baguette). Can be made gluten-free using gluten-free bread. Contains alcohol (wine) - most cooks off during preparation. Always check broth labels for potential allergens. Always check ingredient labels if you have food allergies. Keyword bistro soup, caramelized onion soup, cheese soup, classic onion soup, comfort soup, French bistro, French onion soup, Gruyère soup