Slow Cooker French Onion Soup

Name: The Best Slow Cooker French Onion Soup
Prep time: 15 min
Cook time: 9 h
Total time: 555 min
Yield: 2
Ingredients: 4 large onions sliced; 30 g (~ 2 tbsp) butter, roughly chopped; 1 tbsp caster sugar; 1 tbsp balsamic vinegar; 2 tsp minced garlic or garlic puree; 1 tsp dried thyme; 1 tsp black pepper; 750 ml (~ 3 cups) vegetable stock; 2-4 thick slices French baguette; 2-4 tbsp grated cheese (I used cheddar)

by Becca

2 people

9 hr 15 min

Let your appliance do all the hard work to make this spectacular slow cooker French onion soup! It’s rich and flavourful, and topped with a giant cheesy crouton. You can find more details about the recipe on Easy Cheesy Vegetarian.

best slow cooker french onion soup recipe

If you like it when your dinner cooks itself, you’ll love this slow cooker French onion soup. It’s rich and earthy, sweet and tangy, and all-round wonderful. Add a super cheesy crouton, and you may as well just marry it now.

Slow Cooker French Onion Soup

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Recipe details

Yield 2 people
Time spent: Prep time: 15 Minutes Cook time: 9 Hours Total time: 9 hr 15 min

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Ingredients

For the slow cooker French onion soup:

4 large onions sliced
30 g (~ 2 tbsp) butter, roughly chopped
1 tbsp caster sugar
1 tbsp balsamic vinegar
2 tsp minced garlic or garlic puree
1 tsp dried thyme
1 tsp black pepper
750 ml (~ 3 cups) vegetable stock

For the cheesy crouton:

2-4 thick slices French baguette
2-4 tbsp grated cheese (I used cheddar)

Instructions

Add all of the soup ingredients to a slow cooker, and mix well to break up the onions. Cook on high for approximately 9 hours, or until the onions are a deep, rich brown colour, and very soft.
Serve on its own, or with a cheesy crouton. To make the cheesy crouton, dish up a bowlful of soup into a heat-safe bowl, and top with 1 or 2 thick slices of French baguette. Sprinkle over plenty of grated cheese, then place under a grill (broiler) for a few minutes, until the cheese is melted and slightly crispy. Serve immediately.

Comments

Julia on Nov 12, 2021

9 hours on high?

56 Reply
- See 4 previous
- Connie Hardman on Nov 12, 2021
  
  That’s what I was thinking too! Lol
  
  14
- Jenni on Nov 13, 2021
  
  Oh my. I don’t think so. You’d have no soup left lol. I’m going low lol
  
  7
- Kristine McGill-Arneson on Nov 15, 2021
  
  I did mine on high and it came out just fine. I added a bit more stock as I had way to many onions but had plenty of broth in the end.
  
  12
- Sig188114929 on Nov 03, 2025
  
  I was wondering about the HIGH setting also. 🧅🧄🧅
  
  19
- Psh112411348 on Aug 17, 2026
  
  The onions need to get carmelized, not just soft. It’s a long process on a stovetop also.
  
  8
Eve on Nov 12, 2021

Seriously…..high?

40 Reply