Slow Cooker French Onion Soup (The BEST!)

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Caramelized onions swimming in a rich velvety broth topped with toasted French bread and melted gourmet cheeses! And, it can be made healthy!!!

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Slow Cooker French Onion Soup is bursting with caramelize onions, fresh herbs, and a delicious broth! My father loved to cook, and he was most intrigued with French and Italian foods. As a child, his French Onion Soup was my favorite! Certain recipes bring back beautiful memories of homemade soups, breads, donuts (YUM!), and many other recipes that he perfected with his natural talent. This soup was served in the same little 1970s crock pots shown in the pictures throughout this blog. The broth is rich and velvety with caramelized onions topped with toasted French bread and melted gourmet cheese. Definitely one of my fall regulars when I’m in the mood for a heartier soup!

French Onion Soup Recipe

Lighter and Gluten-free option (And still amazing!)

During those times when I am trying to eat a little lighter, I still crave this yummy soul-warming soup. It takes only a few easy alterations to make Slow Cooker French Onion Soup healthy and guilt-free!

  • When caramelizing the onions, use coconut sugar in place of the brown sugar. Coconut sugar is a light brown all-natural sugar made from the coconut that will not affect the flavor of the onions.
  • Leave off the French bread, or use a gluten-free bread in its place. If using gluten-free bread, cut the broiling time down because it can easily burn.
  • If you want this dish to be dairy-free, you can leave off the cheese. I have eaten this soup on many occasions without the bread or the cheese, and I didn’t miss a thing! Seriously, the broth and onions are that good!

Favorite Soup Recipes


How to make Slow Cooker French Onion Soup

This recipe requires a little bit of prep work, but afterwards you can throw it in a slow cooker and forget it for 6 hours! Maybe “pour” it in a slow cooker is more accurate. I don’t want you to end up with onion splashes all over your kitchen!

Equipment Used

Ingredient List

  • Caramelized Onions – yellow onions, butter, brown sugar
  • Herbs – thyme, bay leaf
  • Soup – garlic, beef broth, Worcestershire sauce, sherry
  • Cheese – Gruyere, Provolone
  • Bread – French baguette

Recipe Preparation

  • The first step is to peel and thinly slice the onions into 2 to 3 inch slices depending upon the size of the onion. To do this, cut the onion in half, then slice the halves into thin slices. Some recipes ask that you slice the onions into thin “rings.” While this method is easier to do, I do not choose it because the longer the onions, the messier they are to eat. It’s simply a matter of preference.
Caramelized Onions
  • In a large Dutch oven, or heavy-bottomed pot, add the butter and brown sugar allowing the butter to melt. Add the onions and sauté on medium heat until they are tender and golden brown (caramelized). This will take about 20 minutes. Stir often to prevent onions from burning.
  • Pull a clove out of a head of garlic. Peel the clove then mince it by chopping it into very small pieces.
French Onion Soup
  • Add caramelized onions, bay leaf, thyme, broth, Worcestershire sauce, garlic, and sherry to the slow cooker. Cook soup on LOW for 6 hours. Don’t want to use Sherry? You can easily substitute red wine vinegar for sherry in this recipe. You can also choose to leave out the Sherry with no replacement, but your final result will miss the sweet/savory flavor that this ingredient adds.
  • When soup is ready to serve, slice a French baguette into 3/4-inch slices and brush top lightly with olive oil. Broil slices 5 to 6 inches from the top burner for 1 to 2 minutes on each side, or until bread is toasted and light golden brown.
Slow Cooker French Onion Soup
  • Pour Slow Cooker French Onion Soup into individual OVEN SAFE bowls, making sure there is an ample amount of onions in each. Place a piece of toasted bread on top of the soup. Sprinkle bread with shredded cheese, then top with a round slice of Provolone. Broil in oven for 2 to 3 minutes, or until cheese is melted and bubbly. When serving, remember that the bowls are HOT and your guests will need pot holders for safety.
slow-cooker-french-onion-soup-recipe-heather-lucilles-kitchen-food-blog

Slow Cooker French Onion Soup

Caramelized onions swimming in a rich velvety broth topped with toasted French bread and melted gourmet cheeses! And, it can be made healthy!!!
5 from 2 votes
Print Pin Rate
Course: Soups and Salads
Cuisine: French
Servings: 6
Calories: 284kcal

Ingredients

  • 3 large yellow Onions sliced very thin
  • 2 Tbsp brown sugar
  • 3 Tbsp butter
  • 1 bay leaf
  • 4 sprigs fresh thyme
  • 64 oz beef broth
  • 1 Tbsp Worcestershire sauce
  • 1 clove garlic minced
  • 1/2 cup sherry
  • Gruyere cheese shredded
  • Provolone slices
  • 1 French loaf sliced

Instructions

  • In a large Dutch oven, or heavy-bottomed pot, add butter and brown sugar, allowing the butter to melt. Add onions and sauté on medium heat until they are tender and golden brown (caramelized). This will take about 20 minutes. Stir often to prevent onions from burning.
  • Add caramelized onions, bay leaf, thyme, broth, Worcestershire sauce, garlic, and sherry to the slow cooker. Cook soup on LOW for 6 hours.
  • When soup is ready to serve, slice a French baguette into 3/4-inch slices and brush top lightly with olive oil. Broil slices 5 to 6 inches from the top burner for 1 to 2 minutes on each side, or until bread is toasted and light golden brown.
  • Pour soup into individual OVEN SAFE bowls, making sure there is an ample amount of onions in each. Place a piece of toasted bread on top of the soup. Sprinkle bread with shredded cheese, then top with a round slice of Provolone. Broil in oven for 2 to 3 minutes, or until cheese is melted and bubbly. When serving, remember that the bowls are HOT and your guests will need pot holders for safety.

Notes

Lighter and Gluten-Free Option:
  • When caramelizing the onions, use coconut sugar in place of the brown sugar. Coconut sugar is a light brown all-natural sugar made from the coconut that will not affect the flavor of the onions.
  • Leave off the French bread, or use a gluten-free bread in its place. If using gluten-free bread, cut the broiling time down because it can easily burn.
  • If you want this dish to be dairy-free, you can leave off the cheese. I have eaten this soup on many occasions without the bread or the cheese, and I didn’t miss a thing! Seriously, the broth and onions are that good!
 

Nutrition

Calories: 284kcal | Carbohydrates: 50g | Protein: 12g | Fat: 2g | Saturated Fat: 1g | Fiber: 3g | Sugar: 10g

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