This low-carb version of French onion soup is cheesy and flavorful. Make this healthy yet comforting soup in your slow cooker or Instant Pot.

Slow Cooker/Instant Pot Low-Carb French Onion Soup (Keto)

  • Author: Fit SlowCooker Queen
  • Prep Time: 10 minutes
  • Cook Time: 4 hours
  • Total Time: 4 hours 10 minutes
  • Yield: 6-8 bowls 1x


  • 2 large white onions, sliced thin (approximately 2 pounds)
  • 6 cups low-sodium beef or bone broth
  • 2+ cups cheese, grated (approximate)
  • 1 tbsp ghee or butter
  • 1 garlic clove, minced
  • 1/2 tsp salt
  • 1/2 tsp dried thyme
  • 1/4 tsp pepper
  • 1 bay leaf (I used 2 small)


Slow Cooker

  1. Add all the ingredients EXCEPT the cheese to the slow cooker. Stir to mix well.
  2. Cook HIGH 3-4 hours, LOW 6-8. Remove bay leaf.
  3. See FINAL STEP below

Instant Pot

  1. Set Instant Pot to the high saute setting. Heat ghee/butter. When hot, add onion and garlic and cook, stirring occasionally, until tender, about 4-6 minutes.
  2. Pour in broth and using a wooden spoon scrape well the bottom of the Instant Pot to remove any bits that stuck to it, make sure you scrape it well to avoid burning during cooking. Add bay leaf, salt, pepper, and thyme.
  3. Close lid and seal valve. Set high pressure and cook for 25 minutes, natural release. Remove bay leaf.
  4. See FINAL STEP below

FINAL STEP (you will need ovenproof bowls)

Preheat broiler. Ladle the soup evenly into bowls & top evenly with shredded cheese. Arrange bowls on a large baking sheet. Place baking sheet carefully under the boiler and broil a few minutes or until cheese is melted and starting to brown slightly.