Name: Weeknight French Onion Soup
Prep time: 10 min
Cook time: 12 h 30 min
Total time: 12 h 40 min
Yield: 4 servings
Cuisine: French
Ingredients: 2 pounds white onions, thinly sliced; 1/4 cup unsalted butter, cut into chunks; 4 sprigs fresh thyme; 1 teaspoon salt; 1/2 cup dry white wine; 1 tablespoon flour; 1 (32-oz) box of beef broth (see note); 1 bay leaf; 1 tablespoon Worcestershire sauce; 8 slices French bread (see note), toasted; 8 ounces Gruyere cheese, grated

Use your slow cooker to make warm and cozy french onion soup a reality during the week.

French Onion Soup

I shared a recipe for crockpot mashed potatoes back in November and in that post, I mentioned something about not loving my crockpot. Right after that, I spun around and asked Santa to bring me a shiny new slow cooker for Christmas (my old one was olllld… 17 years old, I think) because, seriously, why haven’t I embraced crockpot cooking in the six-plus years I’ve been writing this blog?

So I decided to challenge myself and get back on the slow cooker horse starting with a classic French onion soup after learning that a slow cooker is a great hands-off way to caramelize onions. Normally, you’d have to spend at the least 45 minutes to an hour standing over the stove to get the same result making French onion soup a great dish to make on the weekend, but a terrible one for mid-week. Who has time to caramelize onions on a Tuesday night?

How to Caramelize Onions in a Slow Cooker

The best part about using your slow cooker to caramelize the onions is that it’s a hands-off operation. The trade-off is that you won’t get deeply golden browned onions that you would otherwise get if you caramelized them on the stove, but they still come out the slow cooker tender and sweet. The trade-off is worth it for me to be able to have a cozy bowl of French onion soup on a random Tuesday that would otherwise require a half-day off work if I made it from start to finish on the stove.

I like to use white onions for this recipe and you’ll want to slice two pounds of them.
Place them in the slow cooker along with butter and some sprigs of fresh thyme.
Cook them on low for 10 to 12 hours. I like to do this the night before I want to have the soup for dinner. I stir them after they’ve been in the slow cooker for three hours or so. The next morning I give them another stir an hour or so before they’re done.
Transfer the cooked onions (be sure to remove the thyme springs!) to a container along with all of the liquid in the slow cooker. Pop them in the fridge until you’re ready to make the soup.

How to Make French Onion Soup

Once the slow cooker caramelized onions are done the soup comes together in about 30 minutes.

Warm the onions and their liquid over medium heat in a pot.
Add some white wine and simmer it with the onions.
Sprinkle some flour over the top and stir to coat the onions in it. The flour will help thicken the soup a bit.
Add the beef broth, some Worcestershire sauce, and a bay leaf and bring the soup to a boil and reduce the heat to maintain a simmer.
While the soup is simmering, toast some sliced bread (I like to use a thin baguette) under the broiler and grate some gruyere cheese.
Ladle the soup into oven-safe bowls and place them on a sheet pan. Top each soup bowl with a few slices of toasted bread and pile some gruyere cheese on top. Transfer them under the broil just until the cheese is melted and bubbling.

Hello, weeknight French onion soup.

The toast soaks up all the brothy goodness and the cheese – that cheese! I am in love with the ooey-gooey gruyere cheese. One bite and you’ll feel like you’re sitting in a French bistro far, far away from your normal it’s-just-another-Tuesday-night situation.

All thanks to a slow cooker.

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