Slow Cooker French Onion Soup | Mulling it to Miller

Slow Cooker French Onion Soup

Oh the weather outside is frightful! Seriously, can Spring make up its mind yet? One day the sun is out and shining a beautiful 80*. Then the next we have sub 40* temperatures with rain. The constant yo-yo has me craving some comfort food to warm the soul … and maybe my fingers.

With that said, here is a recipe for soup! Not just any soup, but the king of soups: French onion soup. You’ve probably ordered this dish once or twice while at a restaurant and just savored every last bite of this cheese-covered soup thinking to yourself “this is absolutely the best soup in the world.” Am I right? Of course I am because NOTHING beats a great crock of French Onion Soup on a cold, blistery day.

From the beefy broth, the flavorful caramelized onions, the broth-soaked bread to the cheese — the golden, bubbling layer of perfection to top of this amazing bowl of yumminess. While I think we can all admit how much we LOVE French Onion Soup, few and far between have actually made it at home. Even though it looks intricate (AKA a complex, tricky recipe), it’s actually quite EASY! PLUS, we made it even easier with our slow cooker version!

So what are you waiting for? Go make a pot. And enjoy this perfect soup all winter long… or you know, Spring, whichever tickles your fancy.



French Onion Soup

Course Soup
Servings 8 bowls
Author Courtney & Steve


Onion Mixture

  • 2 tbs Brown Sugar dark
  • 3 tbs Butter
  • 5 Yellow Onions quartered

Soup Mixture

  • 8 sprigs Thyme stripped
  • 1/4 cup Sherry
  • 1 tbs Worcestershire Sauce
  • 5 cloves Garlic minced
  • 1/4 cup Balsamic Vinegar
  • 1 cup Red Wine dry
  • 64 oz Beef Stock reduced sodium
  • 3 Bay Leaves


  • Baguette sliced
  • 2 cups Gruyere cheese shredded
  • 2 cups Mozzarella cheese shredded
  • 2 cups Swiss cheese shredded


  1. Melt butter in a large skillet over medium-low heat. Add onions, cooking until soft - stirring occasionally for about 15-20 minutes. Add sugar with salt & pepper to taste; continue to cook, stirring occasionally until onions are deep golden brown and caramelized, reducing heat slightly if onions seem to be browning too quickly (approximately 20 - 30 minutes).
  2. Add the ingredients from Step 1 (onion mixture) into your crockpot, combining with ingredients from Soup mixture. Stir until all ingredients are combined. Cover and cook on low for 6 to 8 hours. The longer you cook the soup, the more intense the flavors will be!
  3. Place the slices of baguette on a baking pan and toast (I use the broil part of my oven for approximately 2 minutes on each side).

  4. Portion the soup into oven-safe bowls and place on top a baking pan for ease. I then add a nice portion of Mozzarella & Swiss cheese into the mixture before placing my pieces of baguette. I top the baguette with generous amounts of Gruyere cheese. Place the bowls in the oven to bake at 350*F for approximate 20 to 30 minutes to melt the cheese.

    If you are like me, you like the crispy melted cheese - to achieve this, broil the soup bowls for an additional 2 to 3 minutes after baking so the cheese is bubbly & browned.

Recipe Notes

If you don't have crock bowls, I highly suggest you invest in some. I have found these on Amazon (affiliate link), but if you would like to search on your own a key thing to look out for is the handles. Some are hollow and crack/shatter with heat (just check your reviews) 🙂

Amazon Soup Crocks



  1. SEO Mechanic | 28th Apr 17

    This looks delicious

    • Courtney & Steve | 28th Apr 17

      It was and with the weather so up and down, soup is just what I needed.

Leave A Comment

We would love to know your thoughts!