Slow Cooker French Onion Soup Recipe
Whether you’re a novice or a chef, get ready to impress your guests with the best Slow Cooker French Onion Soup Recipe! This easy, made-from-scratch soup is all about the flavor – sweet caramelized onions simmered in a rich, savory broth. Soup lovers can’t get enough of the gourmet-worthy taste made right in your own kitchen!
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What’s To Love About This Recipe
- This recipe tastes like luxury straight from your slow cooker! It’s a true set-it-and-forget-it soup that yields the rich flavors of caramelized onions. There is no stovetop babysitting, which makes it an excellent choice for all-day cooking on low heat.
- The flavor is complex and deep, but made from simple ingredients. It’s also a budget-friendly recipe, but totally feels gourmet!
- It couldn’t be easier to throw this together before a busy day. Simply slice the onions, add the ingredients to the slow cooker, and make a few adjustments before serving.
- Balsamic glaze and herbes de Provence give a unique twist to a classic dish. Your kitchen will smell amazing with the aromatic herbs simmering away all day!
- French onion soup is a perfect choice for cozy weeknight dinners or an easy entertaining starter. With the slow cooker doing the work, your hands are free to work on other sides or entrées.
- The savory, brothy soup pairs beautifully with crusty French bread slices, toasted baguettes, or a simple side salad.
Ingredients Needed
- Unsalted butter – Butter adds the necessary fat to cook and caramelize the onions, giving them a rich glaze.
- Yellow or sweet onions – Thinly sliced yellow or sweet onions are ideal for achieving a balance of flavor and sweetness. For a bolder taste, add some red onions.
- Garlic – Smash some cloves of fresh garlic to add complexity to the soup and balance the sweetness of the onions.
- Balsamic glaze – The acidity adds a subtle sweetness that cuts through the richness of the soup, and the glaze creates a thicker consistency than vinegar. You can also substitute with balsamic vinegar if needed.
- Herbes de Provence – This traditional blend adds a fragrant, slightly floral flavor profile. Italian seasoning can also be swapped if that’s what you have on hand.
- Salt and black pepper – These enhance the overall flavor and add a mild kick. Increase the salt near the end to taste.
- Beef bone broth and chicken bone broth – Using a combination of beef and chicken bone broth adds depth and richness to the soup base. A rustic, homemade broth is ideal, but store-bought options work well too.
- Parmesan cheese crisps – These crispy pieces add a salty, crunchy topping alternative to traditional bread and melted cheese. Add them just before serving the soup.
How To Make Slow Cooker French Onion Soup
- Place sliced onions, butter, balsamic glaze, Herbes de Provence, salt, and pepper into the slow cooker. Stir to coat the onions evenly.
- Cover and cook on high for 6-7 hours or low for 10-12 hours, stirring occasionally if possible, until the onions are deep golden and caramelized.
- Once the onions are caramelized, add the beef and chicken broth (and optional Worcestershire sauce). Stir to combine.
- Cover and cook for an additional 30-60 minutes on high to allow the flavors to meld.
- Top with Parmesan cheese crisps as desired.
Pro Tips
- Slice the onions with uniform thickness to ensure even caramelization.
- Caramelizing directly in the slow cooker is a low-maintenance option, but for even deeper flavor, you can start them on the stovetop before transferring to the slow cooker.
- Taste and adjust the salt near the end of cooking. The broths will vary in sodium levels, and you may prefer a bit of extra salt once everything has cooked.
- For a more classic presentation, top oven-safe dishes of French onion soup with Gruyère, provolone, or mozzarella cheese and broil to finish in the oven. Add toasted baguette slices to complete it!
Recipe Substitutions and Variations
- Use a mix of yellow, sweet, or red onions for layered flavors. Be sure to slice them all evenly for consistent cooking and caramelization.
- Vary the recipe with your choice of broth. Use a store-bought or homemade bone broth for extra protein and nutrients, or substitute vegetable broth for a vegetarian version. You can also adjust the sodium level by using a no-sodium-added broth.
- The classic way to serve French onion soup includes a thick layer of cheese melted over a cup or small crock of soup. Use Gruyère, Swiss, or provolone for a more traditional cheesy topping.
- Substitute thyme or rosemary for herbes de Provence for a simpler herbal profile.
How To Serve French Onion Soup
No cup of French onion soup is complete without a little crispy something on the side to soak up the broth. Whether it’s toasted baguette slices, croutons, or cheesy French bread for dipping, this addition makes an irresistible dish!
For a decadent bistro-style lunch, add a half sandwich or panini with a cup of soup. Or, to complete a dinner meal, serve with a light Caesar or spinach salad, Slow Cooker Roasted Fall Vegetables, or Oven Roasted Carrots. Pair with your favorite glass of wine as a finishing touch!
If you’re in an autumnal state of mind, you might add a tasty home-cooked dessert like Apple Crisp or Caramel Apple Cheesecake Bites.
Storing and Reheating
How To Best Store Leftovers
Fridge
Store leftover soup in an airtight container in the fridge for up to 4 days.
How To Best Reheat Leftovers
Warm the soup gently on the stovetop over medium-low heat, or in the microwave in short intervals. Add fresh Parmesan crisps or toast fresh bread before serving.
Slow Cooker French Onion Soup Recipe
Whether you’re a novice or a chef, get ready to impress your guests with the best Slow Cooker French Onion Soup Recipe! This easy, made-from-scratch soup is all about the flavor – sweet caramelized onions simmered in a rich, savory broth. Soup lovers can’t get enough of the gourmet-worthy taste made right in your own kitchen!
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Equipment
- Slow Cooker
Ingredients
- 3 tablespoons unsalted butter
- 2 pounds about 4 large yellow or sweet onions thinly sliced
- 4 cloves garlic smashed
- 1 tablespoon balsamic glaze
- 1 teaspoon herbes de Provence
- ½ teaspoon salt or to taste
- ¼ teaspoon black pepper
- 3 cups beef bone broth
- 3 cups chicken bone broth
- Parmesan cheese crisps for topping
Instructions
- Place sliced onions, butter, balsamic glaze, Herbes de Provence, salt, and pepper into slow cooker. Stir to coat onions evenly.
- Cover and cook on high for 6-7 hours or low for 10-12 hours, stirring occasionally, until onions are deep golden and caramelized.
- Once onions are caramelized, add beef and chicken broth (and optional Worcestershire sauce), and stir to combine.
- Cover and cook for an additional 30-60 mins on high to allow flavors to meld.
- Top with Parmesan cheese crisps as desired.
Notes
- Store leftover soup in an airtight container in the fridge for up to 4 days.
- Reheat soup gently on the stovetop over medium-low heat or in the microwave in short intervals.
- Slice onions evenly to ensure consistent caramelization.
- For a deeper flavor, start caramelizing the onions on the stovetop before slow cooking.
- Adjust the salt to taste near the end of cooking.
- For a classic finish, top with cheese (such as Gruyère, provolone, or mozzarella), then broil until melted. Serve with toasted baguette slices or crusty sliced bread.
Nutrition
Calories: 142kcalCarbohydrates: 17gProtein: 7gFat: 6gSaturated Fat: 4gPolyunsaturated Fat: 0.3gMonounsaturated Fat: 2gTrans Fat: 0.2gCholesterol: 17mgSodium: 682mgPotassium: 254mgFiber: 3gSugar: 7gVitamin A: 187IUVitamin C: 12mgCalcium: 48mgIron: 1mg
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Important nutritional disclaimer