Slow Cooker French Onion Soup Recipe

Onions: Thinly sliced to caramelize and bring out their natural sweetness.

Butter: Used to caramelize the onions, adding richness to the soup.

Garlic: Adds a subtle, aromatic flavor to the soup.

Beef broth: The base of the soup, providing depth and a savory taste.

Red wine: Optional, but adds complexity and enhances the flavor of the broth.

Thyme: A dried herb that adds an earthy, slightly minty flavor.

Bay leaf: Adds a subtle, herbal note to the soup.

Salt: Enhances the overall flavor of the soup.

Pepper: Adds a touch of heat and balances the flavors.

Baguette: Sliced and toasted to serve as a crunchy topping.

Gruyère cheese: Grated and melted on top of the toasted baguette for a creamy, nutty finish.

When caramelizing onions, patience is key. Cook them slowly over medium heat, stirring occasionally, to achieve a deep, rich color and flavor. This process can take up to 20 minutes, but it's essential for developing the soup's signature taste. If the onions start to stick, add a splash of beef broth to deglaze the pan and incorporate those flavorful browned bits back into the mixture.

• 6 large thinly sliced onions - Substitute with shallots: Shallots have a milder and sweeter flavor, which can add a different depth to the soup.

• 4 tablespoons butter - Substitute with olive oil: Olive oil is a healthier fat option and can provide a slightly different but pleasant flavor.

• 2 cloves minced garlic - Substitute with garlic powder: Use ¼ teaspoon of garlic powder per clove of garlic for a similar flavor profile.

• 8 cups beef broth - Substitute with vegetable broth: Vegetable broth is a good vegetarian alternative that still provides a rich flavor.

• 1 cup optional red wine - Substitute with balsamic vinegar: Balsamic vinegar can add a similar depth and acidity to the soup.

• 1 teaspoon dried thyme - Substitute with dried oregano: Dried oregano has a robust flavor that can complement the other ingredients well.

• 1 bay leaf - Substitute with dried basil: Dried basil can add a different but pleasant aromatic note to the soup.

• salt and pepper - Substitute with soy sauce: Soy sauce can add saltiness and umami flavor to the soup.

• 1 baguette sliced and toasted - Substitute with sourdough bread: Sourdough bread has a tangy flavor and a chewy texture that works well when toasted.

• 2 cups grated gruyère cheese - Substitute with Swiss cheese: Swiss cheese has a similar nutty flavor and melts well, making it a good alternative.

• Allow the French onion soup to cool to room temperature before storing. This helps prevent condensation, which can lead to a watery soup.

• Transfer the cooled soup into airtight containers. For easy portioning, consider using individual serving-sized containers.

• Label each container with the date of preparation. This ensures you keep track of freshness and consume the soup within a safe timeframe.

• Store the soup in the refrigerator if you plan to consume it within 3-4 days. The flavors will continue to meld, making it even more delicious.

• For longer storage, place the airtight containers in the freezer. The French onion soup can be frozen for up to 3 months without losing its rich flavor.

• When ready to enjoy, thaw the soup in the refrigerator overnight. This slow thawing process helps maintain the soup's texture and flavor.

• Reheat the soup gently on the stovetop over medium heat, stirring occasionally. If the soup has thickened too much, add a splash of beef broth or water to reach the desired consistency.

• For a quick reheating option, use the microwave. Transfer the soup to a microwave-safe bowl, cover loosely, and heat in 1-minute intervals, stirring in between until hot.

• If you have leftover baguette slices and gruyère cheese, store them separately. Keep the toasted baguette in an airtight container at room temperature for up to 2 days. The grated cheese can be stored in the refrigerator in a sealed bag or container for up to a week.

• When serving reheated soup, follow the original recipe's final steps: top with a slice of toasted baguette, sprinkle with grated gruyère cheese, and broil until the cheese is melted and bubbly. This ensures each bowl is as delightful as the first.

• For stovetop reheating:

  1. Pour the leftover French onion soup into a saucepan.
  2. Heat over medium-low, stirring occasionally to ensure even warming.
  3. Once the soup is hot, ladle it into bowls.
  4. Top with a slice of toasted baguette and sprinkle with grated gruyère cheese.
  5. Broil until the cheese is melted and bubbly.

• For microwave reheating:

  1. Transfer a portion of the soup into a microwave-safe bowl.
  2. Cover the bowl with a microwave-safe lid or a plate.
  3. Heat on high for 2-3 minutes, stirring halfway through.
  4. Ensure the soup is heated evenly and thoroughly.
  5. Top with a slice of toasted baguette and sprinkle with grated gruyère cheese.
  6. Microwave for an additional 30 seconds to 1 minute until the cheese is melted.

• For oven reheating:

  1. Preheat your oven to 350°F (175°C).
  2. Pour the leftover soup into an oven-safe dish.
  3. Cover the dish with aluminum foil to prevent drying out.
  4. Heat in the oven for about 20-25 minutes or until hot.
  5. Remove from the oven, ladle into bowls, and top with a slice of toasted baguette.
  6. Sprinkle with grated gruyère cheese and broil until the cheese is melted and bubbly.

• Large skillet: Used to melt the butter and caramelize the onions over medium heat.

• Slow cooker: Essential for cooking the soup on low for 8 hours, allowing the flavors to meld together.

• Wooden spoon: Handy for stirring the onions and garlic while they cook.

• Garlic press: Useful for mincing the garlic cloves efficiently.

• Measuring cups: Needed to measure out the beef broth and optional red wine accurately.

• Measuring spoons: Used to measure the thyme, salt, and pepper.

• Cutting board: Provides a surface for slicing the onions and baguette.

• Chef's knife: Essential for thinly slicing the onions and cutting the baguette.

• Grater: Used to grate the gruyère cheese before topping the soup.

• Baking sheet: Needed for toasting the baguette slices in the oven.

• Broiler: Used to melt and bubble the gruyère cheese on top of the soup.

• Ladle: Handy for serving the soup into bowls.

• Soup bowls: Used to serve the final dish.

• Tongs: Useful for handling the toasted baguette slices when placing them on the soup.

Pre-caramelize onions: Caramelize onions in bulk and freeze portions for future use.

Use pre-minced garlic: Save time by using store-bought minced garlic instead of mincing fresh cloves.

Broth shortcuts: Opt for high-quality beef broth from the store to skip making it from scratch.

Wine alternative: If you don't have time to buy red wine, use a splash of balsamic vinegar for a similar depth of flavor.

Cheese prep: Buy pre-grated gruyère cheese to save time on grating.

Toast in batches: Toast multiple slices of baguette at once in the oven to save time.