Save A decadent twist on classic grilled cheese, this sandwich combines caramelized onions with gooey melted cheese for a deeply savory, next-level comfort food experience.
I first served this to my family on a chilly evening and it quickly became a favorite comfort food that everyone eagerly requests again.
Ingredients
- For the Caramelized Onions: 2 tablespoons unsalted butter, 2 large yellow onions thinly sliced, 1 teaspoon sugar, 1/2 teaspoon salt, 1/4 teaspoon freshly ground black pepper, 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried), 1 tablespoon balsamic vinegar
- For the Sandwich: 4 slices sourdough or country style bread, 2 tablespoons unsalted butter softened, 1 cup (about 100 g) shredded Gruyère cheese, 1 cup (about 100 g) shredded mozzarella cheese, 2 teaspoons Dijon mustard
Instructions
- Step 1:
- Melt 2 tablespoons butter in a large skillet over medium heat. Add sliced onions, sugar, salt, and pepper. Cook, stirring occasionally, until onions are golden brown and deeply caramelized, about 2530 minutes.
- Step 2:
- Stir in thyme and balsamic vinegar cook another 2 minutes until fragrant. Remove from heat and set aside.
- Step 3:
- Butter one side of each bread slice. Spread Dijon mustard on the unbuttered side of two slices.
- Step 4:
- Layer half the Gruyère and mozzarella onto the mustard side. Top with a generous spoonful of caramelized onions, then the remaining cheese. Place the other bread slices on top, buttered side facing out.
- Step 5:
- Heat a clean skillet or griddle over medium low heat. Cook sandwiches 35 minutes per side, pressing gently and flipping once, until bread is golden and cheese is fully melted.
- Step 6:
- Let rest 1 minute before slicing. Serve hot.
Save Sharing this sandwich at family dinners creates warm and memorable moments filled with laughter and satisfaction.
Required Tools
Large skillet, Spatula, Bread knife, Cheese grater
Allergen Information
Contains Milk (cheese, butter), Wheat (bread), Mustard. If using store bought bread, check for additional allergens.
Nutritional Information
Calories 540, Total Fat 32 g, Carbohydrates 44 g, Protein 22 g per serving
Save This French Onion Grilled Cheese makes a perfect comforting meal ready in under an hour. Enjoy it freshly made for the best experience.
Recipe FAQ
- → How do I achieve perfectly caramelized onions?
Cook thinly sliced onions slowly in butter over medium heat, stirring occasionally, until golden brown and sweetly soft, about 25-30 minutes.
- → Which cheeses work best for this sandwich?
A mix of Gruyère and mozzarella offers both nutty and creamy textures, easily melting to create a rich filling.
- → Can I use other breads besides sourdough?
Yes, country-style or rustic breads with a sturdy crumb work well to hold the fillings without becoming soggy.
- → What does the balsamic vinegar add to the onions?
It enhances the sweetness and adds subtle acidity, balancing the rich caramelized flavor.
- → How should I cook the sandwich for the best texture?
Use medium-low heat and cook each side 3–5 minutes while pressing gently to achieve a golden crust and fully melted cheese.