Decadent French Onion Soup with Gruyère Toasts Recipe

Why You’ll Love Decadent French Onion Soup with Gruyère Toasts Recipe

I enjoy this recipe because it turns simple ingredients into something truly special. I like how patient cooking brings out the natural sweetness of the onions, and I always appreciate how the melted Gruyère adds a savory, satisfying finish. I also find this soup perfect for cozy dinners and relaxed gatherings.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

4 large onions, thinly sliced
4 tbsp unsalted butter
1 tbsp olive oil
1 tsp sugar
1 tsp salt
1 tbsp all-purpose flour
6 cups beef broth
1/2 cup vegetable broth
1 bay leaf
1 tsp thyme
1 baguette, sliced
1 1/2 cups grated gruyère cheese

Directions

I melt the butter with the olive oil in a large pot over medium heat, then add the onions, sugar, and salt. I cook them slowly, stirring occasionally, until they are deeply caramelized and golden brown. I sprinkle the flour over the onions and stir for a minute to coat them evenly. I pour in the vegetable broth along with the beef broth, then add the bay leaf and thyme and let everything simmer so the flavors come together. While the soup simmers, I toast the baguette slices under the broiler. I ladle the soup into oven-safe bowls, top each with toasted bread and grated Gruyère, and broil until the cheese melts and bubbles before serving hot.

Servings and Timing

I usually prepare this soup to serve 4 people. I spend about 20 minutes on preparation and around 1 hour and 10 minutes cooking, bringing the total time to approximately 1 hour and 30 minutes.

Variations

I sometimes use all vegetable broth for a lighter flavor profile. When I want extra richness, I add a little more butter during the onion caramelization. I also like mixing Gruyère with Swiss cheese for a slightly different taste.

Storage/Reheating

I store leftover soup without the bread and cheese in an airtight container in the refrigerator for up to four days. When reheating, I warm it gently on the stovetop and add fresh toasted bread and cheese just before broiling.

FAQs

Can I make this soup ahead of time?

I often make the soup base a day in advance because the flavors deepen overnight.

What onions work best for this recipe?

I like using sweet or yellow onions because they caramelize evenly and develop great flavor.

Why does caramelizing onions take so long?

I find that slow cooking allows the natural sugars to develop without burning.

Can I freeze this soup?

I freeze the soup base without the bread and cheese for up to three months.

What’s the best bread for the topping?

I prefer baguette slices because they stay sturdy under the melted cheese.

How do I prevent burnt onions?

I keep the heat at medium or medium-low and stir occasionally.

Can I use pre-grated cheese?

I usually grate my own Gruyère because it melts more smoothly.

How thick should the soup be?

I like it lightly thickened, with a rich broth that coats the spoon.

Can I skip the flour?

I can skip it, but I find the soup has a nicer body when I include it.

How do I know when the soup is ready?

I know it’s ready when the onions are tender and the broth tastes deep and savory.

Conclusion

I keep coming back to this French onion soup because it feels timeless and comforting. I enjoy every step, from slowly cooking the onions to breaking through the cheesy topping, and it always turns into a meal worth savoring.