Pin 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 still remember the first time I made these sandwiches for a cozy weekend lunch, and the aroma of onions slowly caramelizing filled my kitchen. Sharing them with friends felt special& this recipe transforms everyday ingredients into a comforting treat.
Ingredients
- Unsalted butter: For caramelizing onions and grilling bread
- Yellow onions: Thinly sliced for a rich sweet base
- Sugar: Helps onions caramelize
- Salt: Balances flavors
- Freshly ground black pepper: Adds a mild kick
- Fresh thyme leaves (or dried): Gives a herbal touch
- Balsamic vinegar: For extra depth and brightness
- Sourdough or country-style bread: Sturdy slices for crisp grilling
- Shredded Gruyère cheese: Melty and nutty
- Shredded mozzarella cheese: For gooey texture
- Dijon mustard: Savory spread for added tang
Instructions
- Caramelize the Onions:
- 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 25&30 minutes.
- Finish the Onions:
- Stir in thyme and balsamic vinegar& cook another 2 minutes until fragrant. Remove from heat and set aside.
- Prep the Bread:
- Butter one side of each bread slice. Spread Dijon mustard on the unbuttered side of two slices.
- Assemble the Sandwiches:
- Layer half the Gruyère and mozzarella onto the mustard side. Top with a spoonful of caramelized onions, then the remaining cheese. Place the other bread slices on top, buttered side facing out.
- Grill the Sandwiches:
- Heat a clean skillet over medium-low heat. Cook sandwiches 3&5 minutes per side, pressing gently and flipping once, until bread is golden and cheese is fully melted.
- Serve:
- Let rest 1 minute before slicing. Serve hot.
Pin My family loves gathering around the kitchen when these sandwiches are sizzling on the skillet& it&s always a race to see who gets the first bite. They&re a favorite for chilly evenings.
Serving Suggestions
Pair your sandwich with tomato soup, a simple green salad or sprinkle a bit of grated Parmesan for extra flavor.
Allergen Information
This recipe contains milk from cheese and butter as well as wheat from bread. Mustard is also present& always check for allergens in store-bought bread or other ingredients.
Nutritional Information
Each serving of this grilled cheese delivers about 540 calories, 32 g total fat, 44 g carbohydrates and 22 g protein.
Pin Enjoy this sandwich hot and melty straight from the skillet with your favorite side. The caramelized onions make every bite unforgettable.
Recipe FAQ
- → How do you achieve perfectly caramelized onions?
Cook sliced onions slowly over medium heat in butter with a pinch of sugar and salt, stirring occasionally for 25-30 minutes until golden and sweetly caramelized.
- → Can I substitute the cheeses used?
Yes, Gruyère can be replaced with Comté or Swiss cheese for a similar creamy melt and flavor profile.
- → What bread works best for this sandwich?
Sourdough or country-style bread provide a sturdy base with a crisp crust and tender crumb, ideal for holding melted cheese and onions.
- → How should the sandwich be cooked?
Cook on medium-low heat in a buttered skillet for 3-5 minutes per side, pressing gently until golden brown with fully melted cheese.
- → Any tips to enhance the flavor?
Adding a splash of dry white wine when cooking the onions or a sprinkle of grated Parmesan before serving adds extra depth and complexity.