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Stacked caramelized onion grilled cheese on a cutting board lined with parchment paper.
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5 from 14 votes

French Onion Grilled Cheese (with Caramelized Onion)

French onion grilled cheese is the best of both worlds: French onion soup AND grilled cheese. This way, you don't have to choose one over the other for dinner - it's like a fancier, grown-up grilled cheese sandwich. Melty, gooey, rich, and toasty, this recipe uses simple ingredients and is easy to make.
Prep Time5 minutes
Cook Time40 minutes
Total Time45 minutes
Course: Main Course
Cuisine: American, French
Diet: Vegetarian
Servings: 2 sandwiches
Calories: 473kcal
Author: MaryAnne

Ingredients

  • 4 Tablespoons unsalted butter
  • 1 yellow onion, sliced into half moons
  • 2 sprigs fresh thyme leaves
  • 1 clove garlic, minced
  • ½ teaspoon salt
  • ¼ teaspoon black pepper
  • 1 Tablespoon white wine vinegar
  • 2 ounces Gruyère (about 3 slices)
  • 2 ounces Swiss cheese (about 3 slices)
  • 4 slices sourdough bread

Instructions

  • Over medium heat, melt 2 tablespoons butter in a large frying pan. Add sliced onion and adjust heat to medium-low. Cook until onion is soft and brown, around 30 minutes, stirring every once in a while.
  • Add thyme, garlic, salt, pepper, and white wine vinegar, and cook for an additional 2 minutes. Transfer onions to a bowl.
  • Use a paper towel to wipe out skillet. Then, adjust heat to low and add remaining 2 tablespoons of butter to pan. Place two slices of sourdough in pan, and distribute cheese evenly over both slices of sourdough. Add onion mixture and place remaining 2 slices of sourdough on top.
  • Cook on one side until golden brown, 5-6 minutes, then flip and cook other side for another 3-4 minutes. Remove from pan and cut in half. Serve immediately.

Video

Notes

    • Go low and slow. When caramelizing onions, be sure to use a low heat setting. You don't want to fry the onions, but instead transform them into silky, soft onions that become slightly sweet.
    • Use high-quality bread. I love the slight tang of sourdough, but use whatever your favorite loaf of bread is. Treat yourself to a nice loaf from your local bakery - it's worth it for this toasted sandwich.
    • How to store: Wrap grilled cheese in foil and store in the refrigerator for up to 4 days; follow reheating instructions below.
    • Avoid pre-grated cheese. Try to avoid pre-grated (shredded) cheese, as it includes additives that prevent it from melting nicely.

Nutrition

Calories: 473kcal | Carbohydrates: 27g | Protein: 15g | Fat: 34g | Saturated Fat: 20g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 9g | Trans Fat: 1g | Cholesterol: 91mg | Sodium: 471mg | Potassium: 115mg | Fiber: 2g | Sugar: 3g | Vitamin A: 971IU | Vitamin C: 1mg | Calcium: 365mg | Iron: 2mg