Slow Cooker French Onion Soup Recipe

overhead view of white soup cup of onion soup and Parmesan crisps with silver spoon on a tan place mat with bowl of Parmesan crisps and salt and pepper shakers in the background

Slow Cooker French Onion Soup Recipe

Whether you’re a novice or a chef, get ready to impress your guests with the best Slow Cooker French Onion Soup Recipe! This easy, made-from-scratch soup is all about the flavor - sweet caramelized onions simmered in a rich, savory broth. Soup lovers can’t get enough of the gourmet-worthy taste made right in your own kitchen!

Course Main Course, Side Dish

Cuisine French

Prep Time 15

Cook Time 8

Total Time 8 15

Servings

Calories 142kcal

Author Jennifer Draper

Equipment

Slow Cooker

Ingredients

3 tablespoons unsalted butter
2 pounds about 4 large yellow or sweet onions thinly sliced
4 cloves garlic smashed
1 tablespoon balsamic glaze
1 teaspoon herbes de Provence
½ teaspoon salt or to taste
¼ teaspoon black pepper
3 cups beef bone broth
3 cups chicken bone broth
Parmesan cheese crisps for topping

Get Recipe Ingredients

Instructions

Place sliced onions, butter, balsamic glaze, Herbes de Provence, salt, and pepper into slow cooker. Stir to coat onions evenly.
Cover and cook on high for 6-7 hours or low for 10-12 hours, stirring occasionally, until onions are deep golden and caramelized.
Once onions are caramelized, add beef and chicken broth (and optional Worcestershire sauce), and stir to combine.
Cover and cook for an additional 30-60 mins on high to allow flavors to meld.
Top with Parmesan cheese crisps as desired.

Notes

Store leftover soup in an airtight container in the fridge for up to 4 days.
Reheat soup gently on the stovetop over medium-low heat or in the microwave in short intervals.
Slice onions evenly to ensure consistent caramelization.
For a deeper flavor, start caramelizing the onions on the stovetop before slow cooking.
Adjust the salt to taste near the end of cooking.
For a classic finish, top with cheese (such as Gruyère, provolone, or mozzarella), then broil until melted. Serve with toasted baguette slices or crusty sliced bread.

Nutrition