Description

This Slow Cooker French Onion Soup recipe delivers a rich, comforting dish made with tender caramelized onions, savory beef broth, and topped with toasted baguette slices and melted Gruyere cheese. Perfect for an easy, hands-off meal that combines deep, classic flavors with minimal effort.

Ingredients

Scale

Soup Ingredients

3 large yellow onions, thinly sliced
1/4 cup butter, cubed
2 teaspoons kosher salt
1 teaspoon fresh ground black pepper
8 cups beef broth or vegetable broth
1/2 cup red wine
1 bay leaf
1 teaspoon dried thyme
2 beef bouillon cubes
2 teaspoons Worcestershire sauce

Toppings

16 slices French Baguette, sliced 1/4-inch thick
8 ounces Gruyere cheese, grated
1/4 cup grated Parmesan cheese

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Instructions

Cook Onions: Place the thinly sliced onions, cubed butter, kosher salt, and freshly ground black pepper in your slow cooker. Cook on high for 3 to 4 hours, stirring occasionally, until the onions are tender and translucent.
Add Broth and Seasonings: Stir the cooked onions, then add the beef or vegetable broth, red wine, bay leaf, dried thyme, beef bouillon cubes, and Worcestershire sauce. Mix well to combine all the flavors.
Slow Cook Soup: Continue cooking on high for another 2 to 3 hours until the onions break down further and the soup develops a rich, deep flavor.
Prepare to Serve: Remove the bay leaf from the soup. Ladle the hot soup into oven-safe bowls or ramekins.
Add Bread and Cheese: Top each bowl with two slices of sliced French baguette and a generous amount of grated Gruyere cheese along with a sprinkle of grated Parmesan cheese.
Broil: Place the bowls on a baking sheet and broil in the oven for 2 to 3 minutes until the cheese is melted, bubbly, and golden brown. Serve immediately and enjoy!

Notes

Stovetop Alternative: Melt the butter in a large Dutch oven over medium heat and sauté the onions for 10-12 minutes until golden and soft. Season with salt and pepper. Add broth, wine, bay leaf, thyme, bouillon, and Worcestershire. Bring to a boil, reduce heat, and simmer uncovered for 1 hour, stirring occasionally. Proceed with broiling the bread and cheese as directed.
You can substitute beef broth with vegetable broth for a lighter flavor or vegetarian option.
Use day-old French baguette slices for better texture when broiled.
Gruyere cheese provides the best melting quality and flavor, but Swiss cheese can be used as a substitute.

Nutrition

Serving Size: 1 bowl (about 1.5 cups)
Calories: 320
Sugar: 8g
Sodium: 850mg
Fat: 15g
Saturated Fat: 9g
Unsaturated Fat: 5g
Trans Fat: 0.2g
Carbohydrates: 28g
Fiber: 3g
Protein: 15g
Cholesterol: 45mg