- Caramelize the Onions:
- In your slow cooker, combine the sliced onions, melted butter, and olive oil. Stir to ensure the onions are well-coated.
- Cover and cook on high for about 4-5 hours or on low for 8-10 hours, stirring occasionally if possible, until the onions are caramelized and browned.
- Add the Broth and Seasonings:
- Once the onions are caramelized, add the minced garlic, beef broth, white wine (if using), bay leaves, thyme, salt, and pepper to the slow cooker. Stir to combine.
- Cover and cook on low for an additional 6-8 hours or on high for 3-4 hours to develop the flavors.
- Prepare the Bread and Cheese:
- Preheat your oven broiler. Place the baguette slices on a baking sheet and broil until they are toasted and golden brown. Set aside.
- In a small bowl, mix together the grated Gruyère and Parmesan cheeses.
- Assemble and Broil the Soup:
- Ladle the soup into oven-safe bowls, leaving enough room at the top for the bread and cheese.
- Place a toasted baguette slice (or two, depending on the size of your bowl) on top of each soup.
- Generously sprinkle the mixed cheeses over the bread and soup, covering the bread completely.
- Place the bowls on a baking sheet and broil in the oven until the cheese is melted and bubbly, about 2-3 minutes. Watch closely to prevent burning.
- Serve:
- Carefully remove the bowls from the oven (they will be hot) and serve immediately. Enjoy the rich, comforting warmth of your Slow Cooker French Onion Soup.
Tips:
- Onion Caramelization: The key to great French onion soup is well-caramelized onions. Don’t rush this step; the slow cooker allows the onions to caramelize perfectly with minimal effort.
- Broth Quality: Use a good-quality beef broth for the best flavor. Homemade broth is ideal, but store-bought works well too.
- Wine Selection: If you choose to add wine, a dry white wine like Sauvignon Blanc works well, adding acidity and depth to the soup.
- Serving Safety: Be cautious when serving and eating the soup, especially if using broiler-safe bowls, as they can become extremely hot.
This Slow Cooker French Onion Soup simplifies the traditional cooking process while delivering all the rich and savory flavors of this classic dish. It’s a perfect meal for cozy nights in, especially when you’re craving something both comforting and effortlessly gourmet.