Classic Slow Cooker Onion Soup is your ticket to comfort in a bowl, with rich flavors and an inviting aroma that fills your home. Perfect for those chilly evenings, this dish transforms simple ingredients into a symphony of taste.
The star of this dish is the yellow onions, which caramelize to bring out their natural sweetness. The combination of butter and olive oil provides a rich base for cooking the onions. A touch of salt helps draw out moisture from the onions, while sugar accelerates caramelization without making the soup sweet. Dry white wine is used to deglaze the pan, adding a layer of acidity that balances the flavors. The beef stock is the backbone of the soup, providing depth and umami. Bay leaves and dried thyme add subtle herbaceous notes. Finally, Gruyère cheese melts beautifully over the toasted baguette slices, creating a delightful, cheesy topping.
This soup pairs wonderfully with a simple green salad dressed in a light vinaigrette. For a heartier meal, consider serving it alongside a charcuterie board with cured meats, olives, and pickled vegetables.
Start by heating the butter and olive oil in a large skillet over medium heat. Once the butter has melted, add the onions, salt, and sugar. Stir occasionally and let them cook for about 30 minutes until they are beautifully caramelized and golden brown. This step requires patience, but it's crucial for developing flavor.
Once the onions are caramelized, pour in the dry white wine to deglaze the pan. Use a wooden spoon to scrape up any brown bits stuck to the bottom — these are flavor gold! Transfer all this oniony goodness to your slow cooker.
Next, pour in the beef stock, and add the bay leaves and dried thyme. Give everything a good stir and set your slow cooker to low. Let it cook for 6 to 8 hours, allowing the flavors to meld together beautifully.
Before serving, taste the soup and adjust seasoning with salt and pepper as needed. Meanwhile, preheat your oven to broil and toast the baguette slices until golden. Top each slice with a generous amount of Gruyère cheese and broil until the cheese is bubbly and melted.
To serve, ladle the hot soup into bowls and crown each with a cheesy baguette slice. Enjoy the comforting, savory flavors with each spoonful.
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