Savory Slow Cooker Onion & Herb Soup

🕒 Prep: 30 min
🔥 Cook: 8 hours
🍽 Serves: 6
★★★★★
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This Savory Slow Cooker Onion & Herb Soup is a cozy, comforting dish that will warm your soul on a chilly day. With a deeply rich flavor profile, thanks to the caramelized onions and fresh herbs, this soup is perfect for when you crave something hearty and satisfying without spending hours in the kitchen.

Ingredients for Savory Slow Cooker Onion & Herb Soup

Yellow onions form the base of our soup. When caramelized, they transform into a sweet, almost jam-like ingredient that gives the soup its depth. Unsalted butter and olive oil start the caramelization process, while the salt and black pepper enhance the natural flavors. Garlic adds a subtle pungency. The fresh herbs, thyme and rosemary, infuse a fragrant earthiness, perfectly balancing the sweetness of the onions. A splash of dry white wine deglazes the pan, lifting all those flavorful bits. Beef broth adds depth and richness, and the bay leaf rounds out the flavor profile. Finally, a touch of Parmesan cheese adds a nutty finish, while the toasted baguette and Gruyere cheese topping bring a delightful crunch and creamy finish.

Tips & Tricks

  • Be patient while caramelizing onions; it’s the key to rich flavor.
  • If your slow cooker runs hot, check the soup at the lower end of the cooking time.
  • Deglaze the pan thoroughly with wine to get all the flavorful bits.

Serving Suggestions

This soup pairs beautifully with a simple green salad topped with a light vinaigrette. For a heartier meal, serve it alongside a platter of assorted cheeses and charcuterie, which complements the soup’s rich flavors.

Frequently Asked Questions

Can I use a different type of onion?
Yes, sweet onions or white onions can work, but they may alter the flavor slightly.
Is there a substitute for the white wine?
You can use chicken broth or a splash of apple cider vinegar as a substitute.
Can I make this vegetarian?
Absolutely! Just swap the beef broth with vegetable broth for a vegetarian version.

Savory Slow Cooker Onion & Herb Soup Recipe Walkthrough

Start by grabbing a large skillet and melting the butter with olive oil over medium heat. Toss in the sliced yellow onions and let them cook down until they're caramelized, about 25 minutes. Stir occasionally to get an even golden color. Once your onions are beautifully caramelized, sprinkle in salt, pepper, and garlic. Give it another 2 minutes, letting the garlic get fragrant.

Next, stir in the thyme, rosemary, and white wine. Let it simmer until the wine reduces by half — this step not only enhances the flavor but also ensures your soup isn’t too boozy. Now, carefully transfer this onion mixture into your slow cooker. Pour in the beef broth and toss in the bay leaf. Stir everything together, ensuring the onions are well distributed in the broth.

Cover the slow cooker and set it to low for 6-8 hours or high for 3-4 hours. This allows all the flavors to meld perfectly. Just before serving, stir in the Parmesan cheese until it's melted and creamy. Ladle the soup into bowls, top with toasted baguette slices, and generously sprinkle with Gruyere cheese. Pop the bowls under a broiler for 2-3 minutes until the cheese is bubbly and golden. Enjoy your delicious creation!

Why You'll Love This Recipe

  • Effortless: Let your slow cooker do most of the work.
  • Rich flavors: Caramelized onions and herbs create an irresistible taste.
  • Perfect for meal prep: Great for leftovers or freezing for later.
  • Customizable: Easily adapt to your taste preferences.

Ingredients

3 lbs yellow onions (sliced)
2 tbsp unsalted butter
1 tbsp olive oil
1 tsp salt
1 tsp black pepper
2 cloves garlic (minced)
1 tbsp fresh thyme leaves
1 tbsp fresh rosemary (chopped)
1/2 cup dry white wine
6 cups beef broth
1 bay leaf
1/4 cup grated Parmesan cheese
1 baguette (sliced and toasted for serving)
1 cup Gruyere cheese (shredded for topping)

Step-by-step Instructions

1. In a large skillet, melt butter with olive oil over medium heat. Add sliced onions and cook until caramelized, about 25 minutes.
2. Add salt, pepper, and garlic to the onions, and cook for an additional 2 minutes.
3. Stir in thyme, rosemary, and white wine. Simmer until wine is reduced by half.
4. Transfer onion mixture to the slow cooker. Add beef broth and bay leaf. Stir to combine.
5. Cover and cook on low for 6-8 hours or on high for 3-4 hours.
6. Before serving, stir in Parmesan cheese until melted.
7. Ladle soup into bowls, top with toasted baguette slices and shredded Gruyere cheese.
8. Place bowls under a broiler for 2-3 minutes, or until cheese is bubbly and golden.

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