Slow Cooker French Onion Soup Recipe

Onions: The star of the dish, providing sweetness and depth when caramelized.

Butter: Adds richness and helps in caramelizing the onions.

Garlic: Enhances the flavor with its aromatic qualities.

White wine: Used to deglaze the skillet, adding complexity to the soup.

Beef broth: Forms the base of the soup, providing a hearty and savory flavor.

Thyme: Adds a subtle earthy note to the soup.

Salt: Enhances all the flavors in the soup.

Black pepper: Adds a hint of spice and balances the flavors.

Baguette: Sliced and toasted, it serves as the perfect crunchy topping.

Gruyere cheese: Melts beautifully over the toasted bread, adding a nutty and creamy finish.

When caramelizing onions, ensure they are sliced evenly to promote uniform cooking. Use a wide skillet to allow maximum contact with the heat, and stir occasionally to prevent burning. This process can take longer than 20 minutes, so be patient and let the onions reach a deep golden brown for the best flavor. Adding a pinch of sugar can help speed up caramelization if needed.

• 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 provides a healthier fat option and can still give a rich flavor to the onions.

• 2 cloves minced garlic - Substitute with garlic powder: Use ¼ teaspoon of garlic powder for each clove to maintain the garlic flavor.

• 1 cup dry white wine - Substitute with apple cider vinegar: Use ½ cup apple cider vinegar mixed with ½ cup water to mimic the acidity and slight sweetness of white wine.

• 8 cups beef broth - Substitute with vegetable broth: Vegetable broth makes the soup vegetarian-friendly while still providing a rich flavor.

• 1 teaspoon dried thyme - Substitute with dried rosemary: Dried rosemary offers a different herbal note that complements the onions well.

• 1 teaspoon salt - Substitute with soy sauce: Use 1 tablespoon of soy sauce to add umami and saltiness to the soup.

• ½ teaspoon black pepper - Substitute with white pepper: White pepper has a slightly different heat and flavor profile but can still provide the necessary spiciness.

• 1 baguette sliced and toasted french bread - Substitute with sourdough bread: Sourdough has a tangy flavor and sturdy texture that holds up well in the soup.

• 2 cups grated gruyere cheese - Substitute with Swiss cheese: Swiss cheese melts well and has a similar nutty flavor to Gruyere.

• Allow the French onion soup to cool completely before storing. This prevents condensation from forming inside the storage container, which can dilute the soup and affect its flavor.

• Transfer the cooled soup into airtight containers. For best results, use containers that are specifically designed for freezing, as they help prevent freezer burn and maintain the soup's quality.

• If you plan to store the soup in the refrigerator, it can be kept for up to 4 days. Make sure the containers are sealed tightly to keep the soup fresh and prevent it from absorbing any other odors from the fridge.

• For longer storage, freeze the soup. It can be frozen for up to 3 months without losing its rich flavor. Label the containers with the date so you can keep track of how long they've been stored.

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

• Reheat the soup on the stovetop over medium heat, stirring occasionally until it is heated through. If the soup has thickened too much during storage, you can add a bit of beef broth or water to reach your desired consistency.

• If you have leftover toasted French bread and gruyere cheese, store them separately in airtight containers. The bread can be kept at room temperature for a day or two, while the cheese should be refrigerated.

• When reheating the soup, follow the original instructions for topping with bread and cheese. Preheat the broiler, ladle the reheated soup into oven-safe bowls, top with the bread slices, and sprinkle with cheese. Broil until the cheese is melted and bubbly, about 2-3 minutes.

• Enjoy your reheated French onion soup as if it were freshly made, savoring the deep, caramelized flavors and the gooey, melted cheese topping.

• Stovetop Method:

  1. Pour the leftover French onion soup into a saucepan.
  2. Heat over medium-low heat, stirring occasionally, until the soup is warmed through.
  3. If the soup has thickened too much, add a splash of beef broth or water to reach the desired consistency.
  4. Ladle the soup into bowls, top with toasted bread slices, and sprinkle with gruyere cheese.
  5. Place the bowls under the broiler until the cheese is melted and bubbly, about 2-3 minutes.

• Microwave Method:

  1. Transfer a portion of the French onion soup to a microwave-safe bowl.
  2. Cover the bowl with a microwave-safe lid or a microwave-safe plate.
  3. Heat on high for 2-3 minutes, stirring halfway through, until the soup is hot.
  4. If the soup is too thick, add a bit of beef broth or water and stir.
  5. Top with toasted bread slices and gruyere cheese.
  6. Microwave for an additional 30 seconds to 1 minute until the cheese is melted.

• Oven Method:

  1. Preheat the oven to 350°F (175°C).
  2. Transfer the leftover French onion soup to an oven-safe dish.
  3. Cover the dish with aluminum foil to prevent the soup from drying out.
  4. Heat in the oven for 20-25 minutes, or until the soup is hot.
  5. Remove the foil, top with toasted bread slices, and sprinkle with gruyere cheese.
  6. Place the dish back in the oven under the broiler for 2-3 minutes until the cheese is melted and bubbly.

• Slow Cooker Method:

  1. Pour the leftover French onion soup back into the slow cooker.
  2. Set the slow cooker to low and heat for 1-2 hours, stirring occasionally, until the soup is hot.
  3. If the soup is too thick, add a bit of beef broth or water and stir.
  4. Ladle the soup into bowls, top with toasted bread slices, and sprinkle with gruyere cheese.
  5. Place the bowls under the broiler until the cheese is melted and bubbly, about 2-3 minutes.

• Large skillet: Used to caramelize the onions and cook the garlic.

• Slow cooker: Essential for cooking the soup slowly over 8 hours to develop deep flavors.

• Wooden spoon: Ideal for stirring the onions and deglazing the skillet.

• Measuring cups: Necessary for measuring the wine and beef broth accurately.

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

• Oven-safe bowls: Required for serving the soup and broiling the cheese-topped bread.

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

• Ladle: Handy for serving the soup into the bowls.

• Cheese grater: Needed to grate the gruyere cheese.

• Knife: Essential for slicing the onions and baguette.

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

• Toaster or oven: Used to toast the baguette slices.

Pre-caramelize onions: Caramelize a large batch of onions ahead of time and freeze portions for future use.

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

Broth shortcuts: Opt for high-quality store-bought beef broth to skip the homemade broth step.

Wine alternatives: If you don't have white wine, use a splash of apple cider vinegar mixed with water.

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

Bread prep: Use pre-sliced and toasted baguette to avoid extra slicing and toasting steps.