Slow Cooker French Onion Soup
This slow cooker French onion soup is ridiculously easy to make, mainly since it cooks in a slow cooker! After you caramelize the onions, it simmers all day, and you come home to an amazing aroma and a fabulous meal for a cold winter day. Using a blend of cheeses on top of the bread makes this soup extra rich and delicious.
Ingredients
- 6 tablespoons butter
- 4 large yellow onions sliced and separated into rings
- 1 tablespoon white sugar
- 2 cloves garlic minced
- ½ cup cooking sherry
- 7 cups reduced-sodium beef broth
- 1 teaspoon sea salt or to taste
- ¼ teaspoon dried thyme
- 1 bay leaf
- 8 slices of French bread
- ½ cup shredded Gruyere cheese
- ⅓ cup shredded Emmental cheese
- ¼ cup freshly shredded Parmesan cheese
- 2 tablespoons shredded mozzarella cheese
Instructions
- Gather all ingredients.
- Heat butter in a large, heavy pot over medium-high heat. Add onions; cook and stir until translucent, about 10 minutes.
- Sprinkle onions with sugar; reduce heat to medium. Cook, stirring constantly, until onions are soft and caramelized, at least 30 minutes. Stir in garlic and cook until fragrant, about 1 minute.
- Stir sherry into onion mixture; scrape the bottom to dissolve the small bits of browned food.
- Transfer onions into a slow cooker and pour in beef broth. Season with sea salt; stir in thyme and bay leaf.
- Cover and cook on Low for 8 to 10 hours or on High for 4 to 6 hours.
- Preheat the oven broiler about 10 minutes before serving. Set an oven rack about 8 inches from the heat source. Arrange bread slices on a baking sheet; broil until toasted, 1 to 2 minutes per side.
- Lightly toss Gruyere, Emmental, Parmesan, and mozzarella cheeses in a bowl.
- Fill oven-safe soup crocks 3/4 full with onion soup and float a bread slice in each bowl.
- Top each with about 2 tablespoons cheese mixture.
- Place filled bowls onto a baking sheet and broil until cheese topping is lightly browned and bubbling, about 2 minutes.
Notes
Cook’s Note
You do not have to caramelize the onions; you can melt the butter in your crockpot, stir in the onions to coat, add the remaining ingredients, and cook. However, caramelizing the onions makes for a much, much better soup!
If you like, put all the soup components — soup, toasted bread, and cheese mixture — out on the table and let people make their soup! This seems to be the favored method when I host a craft night. People can make their own decisions about what they want in or on their soup!