Hands-on Time
30 Mins
Total Time
9 Hours
Serves 12


This slow cooker french onion soup is so easy and delicious, you’ll never return to your stovetop ways. The slow cooker completely eliminates the stirring element of caramelizing onions. After hours in the low heat, the sliced onions will become soft and jammy with a rich, dark brown coloring—no attention necessary. Although you’ll need to start this soup the morning of, you’ll gain nine hours of enticing aromas that will warm your kitchen on a chilly winter day. If you don’t plan to eat it all, freeze the bag of soup in a bowl rather than laying it flat, so it will fit in the saucepan when it's time to thaw. Get ready for this slow cooker french onion soup to be the most requested dish in your house.

How to Make It

Step 1

Place butter, thyme, and bay leaf in the bottom of a 6-quart electric slow cooker. Add onions; sprinkle with sugar. Cover and cook on HIGH for 8 hours.

Step 2

Remove thyme and bay leaf; discard. Add stock, vinegar, salt, and pepper; cook, covered, on HIGH for 30 minutes.

Step 3

Preheat broiler to high.

Step 4

Arrange bread in a single layer on 2 baking sheets; broil 30 seconds on each side or until toasted. Place 1 cup soup in each of 12 (8-ounce) ramekins or ovenproof bowls, or follow freezing instructions. Top each serving with 2 bread slices and about 2 tablespoons cheese. Place 6 ramekins on a jelly-roll pan; broil 2 minutes or until cheese melts and begins to brown. Repeat procedure with remaining 6 ramekins, bread slices, and cheese.

Ratings & Reviews

Sweeter than expected,

March 21, 2015
Next time i'd skip the sugar on top. I even swapped out some red onions, yellow onions and shallots for some of the sweet onions. I also subbed out 1.5 cups of red wine for some of the beef stock. I also let it simmer for longer than the 30 min, i let it sit for 3.5 hours.I liked the ease of the soup. I didn't like the cutting up of onions, that was a kick in the pants. Pretty sure my eyes continued to water long after i stopped cutting them. The other downside is that the onion soup smell stays in the house, even the day after.The overall cost was probably more than a nice dinner with a side of french onion soup. But knowing what i put in the soup is nice to know.For a 2 person household, i might also suggest cutting the recipe in half.The fancy cheese on top gives it a nice earthy ton too. 


March 31, 2015
This was fabulous!!!  Loved the sweetness of the onions.....all the slow cooking made them very tender.  The spices and stock were perfect.  Even my husband (who doesn't like onions) thought it was very good!!  All the taste of the original, but of course, healthier!!

Not bad

September 07, 2015
I like the cooking method but next time I would leave out the vinegar. Should have trusted my original instincts on that one. Other than that it was pretty good.

A solid starter.

March 19, 2015
A good basic recipe. I thought using sweet onions and sugar made the end result a bit too sweet.. but the end result was still comforting on a cold, winter night.

Great Supper Club dish

April 17, 2015
Made this for our "Taste of Spring" themed supper club and it was very well received.  I loved the sweet onion flavor.  I served smaller portions in mugs to go with the rest of the tasting menu.  Reheated it was even better the next day.  I used my food processor to slice the onions, so between that and the slow cooker it was like this dish made itself. I did find that 5 hours on high was long enough to caramelize the onions.

Good reviews!

April 21, 2015
The chopping of onions was not fun but the result was worth it.  The Gruyere cheese and bread on top really made it tasty!  We had a few friends for dinner and everyone seemed to really enjoy it.  I will try the suggestion of adding some red wine to it next time, too.  

Too sweet

May 04, 2015
Perhaps my Vidalia's were too sweet--they are just starting to show up in the grocery, and the soup was too sweet. And perhaps the onions are too juicy too since they didn't really caramelize, rather they just cooked down. I might try again with yellow onions and just a pinch of sugar (if it's really even necessary for the caramelizing process). Not sure if I'll try it again.

Not Good

October 21, 2015
This was way too sweet. French onion soup is savory. I should have went with my first instinct and bought different onions. Also, the vinager is not a good choice. The cooking method was great, however. I will try this method with a different French onion soup recipe.

Better than expected!

January 23, 2018
I had no idea one could caramelize onions in a slow cooker!  Once a year, my hubby will make up a batch of Julia Child's French Onion Soup and it is simply to die for.  This isn't that good, but we still were impressed with the outcome.  I omitted the sugar, but wish I hadn't now.  It did not seem overly sweet to us.  I also did 1 tablespoon of red wine vinegar and 1 tablespoon of pinot noir.  While it was fine, I can't help but wonder if using cognac - as Julia Child does - would add to the richness of the finished soup.  Will try that next time.  A combo of the gruyere along with some sharp cheddar and parmesan (to equal the 7 oz) was a perfect topping.  I also only cooked the onions for 5 hours.  Having a food processor really helps decrease the slicing time and the tears....

Great soup and easy! First time making it!

October 18, 2015
This was my first attempt at making French onion soup. It was really good! I used less onion, 4 large yellow onions, and less sugar, only half tablespoon, as some reviews suggested. I also used cooking sherry instead of the red vinegar. All in all, it was very easy and very tasty! I did have to move it outside to cook as it filled my entire house with the very aromatic onion smell! Not a fan with the kids! But good to eat!! Thumbs up!