Ingredients
Scale
- 2 large yellow onions, thinly sliced
- 2 tbsp unsalted butter (divided)
- 1 tbsp olive oil
- 1 tsp brown sugar (optional, for extra caramelization)
- 1/2 tsp salt
- 4 slices sourdough bread (or your favorite crusty bread)
- 1 1/2 cups shredded Gruyère cheese
- 1/4 tsp black pepper
- 1/4 tsp dried thyme (optional)
Instructions
- Caramelize the onions: In a large skillet over medium-low heat, melt 1 tbsp butter with olive oil. Add onions, salt, and brown sugar. Cook for 25-30 minutes until deep golden brown. Stir in pepper and thyme.
- Assemble the sandwich: Butter one side of each bread slice. On unbuttered sides, layer half the Gruyère, caramelized onions, then remaining cheese. Top with remaining bread, buttered side out.
- Grill to perfection: Heat a clean skillet over medium heat. Cook sandwiches for 3-4 minutes per side until golden brown and cheese is melted.
- Serve: Let rest for 1 minute, then slice and serve immediately.
Notes
- Caramelize onions low and slow for best results
- Gruyère melts beautifully but can be mixed with cheddar or fontina
- Use sturdy, crusty bread to prevent sogginess
- Add Dijon mustard or fig jam for extra flavor
- Best served fresh but onions can be stored for 5 days
- Prep Time: 10 minutes
- Cook Time: 35 minutes
- Category: Lunch
- Method: Stovetop
- Cuisine: American
- Diet: Vegetarian
Nutrition
- Serving Size: 1 sandwich
- Calories: 580 Kcal
- Sugar: 8g
- Sodium: 820mg
- Fat: 32g
- Saturated Fat: 16g
- Unsaturated Fat: 12g
- Trans Fat: 0g
- Carbohydrates: 48g
- Fiber: 3g
- Protein: 24g
- Cholesterol: 75mg
