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French Onion Potato Soup

French onion potato soup simmers deeply golden onions, Yukon Gold potatoes, and beef broth into a creamy, hearty bowl. Serve it with crisp baguette toasts topped with bubbling Gruyere.
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Prep Time 20 minutes
Cook Time 1 hour 12 minutes
Total Time 1 hour 32 minutes
Servings: 8 servings
Course: Dinner
Cuisine: French
Calories: 500
Ingredients Equipment Method Notes

Ingredients
  

For the soup
  • 3 tbsp butter unsalted
  • 1 tbsp olive oil
  • 2 lb yellow onions thinly sliced
  • 1.5 tsp kosher salt
  • 0.5 tsp ground black pepper
  • 3 cloves garlic minced
  • 1 tsp dried thyme
  • 2 tbsp all-purpose flour
  • 0.5 cup dry white wine
  • 8 cup beef broth low-sodium
  • 1.5 lb Yukon Gold potatoes peeled and cut into 1/2-inch cubes
  • 1 bay leaf
  • 0.5 cup heavy cream
For the cheesy toasts
  • 8 baguette slices cut 1/2 inch thick
  • 8 oz Gruyere cheese shredded

Equipment

  • 1 6-quart Dutch oven
  • 1 potato masher
  • 1 rimmed baking sheet

Method
 

Make the soup
  1. Melt the butter with the olive oil in a 6-quart Dutch oven over medium heat.
  2. Add the onions, salt, and pepper, then cook, stirring often and lowering the heat if they begin to scorch, until the onions are deeply golden and reduced, 35–45 minutes.
  3. Stir in the garlic and thyme and cook for 30 seconds.
  4. Sprinkle in the flour and stir for 1 minute.
  5. Pour in the white wine and scrape up the browned bits from the bottom of the pot; simmer until nearly evaporated, 2–3 minutes.
  6. Add the beef broth, potatoes, and bay leaf, bring to a boil, then reduce the heat and simmer until the potatoes are very tender, 15–20 minutes.
  7. Mash about one-third of the potatoes against the side of the pot with a potato masher to thicken the soup.
  8. Stir in the heavy cream and simmer gently for 2 minutes.
  9. Remove the bay leaf.
Make the cheesy toasts
  1. Heat the oven to 425°F and arrange a rack in the upper third.
  2. Place the baguette slices on a rimmed baking sheet and bake, turning once, until crisp and lightly golden, 6–8 minutes.
  3. Sprinkle the Gruyere over the toasted bread and broil on high, about 6 inches from the heating element, until the cheese is melted and bubbling, 1–2 minutes.
  4. Ladle the soup into bowls and top each serving with a cheesy toast.

Notes

Cook the onions low and slow, lowering the heat if they begin to scorch, so they turn deeply golden. Refrigerate leftovers for 3–4 days; freeze the soup without the toasts, preferably before adding the cream for the best texture. For a vegetarian version, use vegetable broth instead of beef broth.