French chefs discovered in 1847 that onions caramelize faster at 185°F than high heat—this technique still confuses home cooks.
Melted Onions with Cheesy Panko Topping
Get ready to indulge in these luscious, caramelized onions that capture the essence of a beloved French onion soup! Topped with a crispy, cheesy panko crust, these savory gems are perfect as a side dish or a delightful appetizer. With a blend of sweet onions and rich broth, they're sure to elevate any meal!
Prep
15
min
Cook
40
min
Serves
4
people
Level
intermediate
📝 Ingredients
Serves 4🥬Fresh Produce(2)
- 3 large sweet onions (12 oz. each), peeled and sliced 1-inch thick
- ½ teaspoon ground pepper (2.5 ml)
🥩Meat & Seafood(1)
- ½ cup lower-sodium beef broth (120 ml)
🥛Dairy & Eggs(3)
- 2 tablespoons unsalted butter, melted, divided (28 g)
- ½ cup shredded Gruyère cheese (120 ml)
- ½ cup shredded low-moisture part-skim mozzarella cheese (120 ml)
🫙Pantry Staples(2)
- 2 tablespoons extra-virgin olive oil (30 ml)
- ⅓ cup panko breadcrumbs (79.2 ml)
🧂Spices & Seasonings(2)
- ½ teaspoon salt (2.5 ml)
- 1 tablespoon plus ½ teaspoon chopped fresh thyme, divided, plus leaves for garnish (15 ml)
🍯Sauces & Condiments(1)
- 1 tablespoon sherry vinegar (15 ml)
👨🍳 Instructions
- 1
Position oven rack in upper third; preheat to 450°F.
- 2
Whisk 2 tablespoons oil, 1 tablespoon melted butter, 1 tablespoon thyme and ½ teaspoon each salt and pepper together in a small bowl. Arrange sliced onions in an even layer in a broiler-safe, 9-by-13-inch metal baking pan. Brush the butter mixture all over the onions. Roast the onions, flipping once halfway, until lightly browned on both sides, about 30 minutes.
- 3
Meanwhile, in the reserved bowl, combine ⅓ cup panko and the remaining 1 tablespoon melted butter and ½ teaspoon thyme; toss until evenly coated. Transfer to a small nonstick skillet; cook over medium-high heat, stirring occasionally, until fragrant and golden brown, 2 to 3 minutes. Remove from heat and allow to cool until ready to use.
- 4
Flip the onions once more. Carefully pour ½ cup broth and 1 tablespoon vinegar into the baking pan. Roast until the broth is slightly reduced and the onions are very soft, about 10 minutes more. Remove from oven.
- 5
Increase oven temperature to broil. Combine ½ cup each Gruyère and mozzarella in a small bowl; evenly sprinkle over the onions. Broil until the cheese is melted and bubbling, about 1 minute. Top with the reserved panko mixture. Garnish with thyme leaves, if desired. Serve with any sauce left in the pan.
💡 Pro Tips
- ✓Flip onions only once at the 15-minute mark to prevent breaking down their cellular structure while ensuring even caramelization on both sides.technique15 minutes
- ✓Toast panko in a dry skillet for 2-3 minutes until golden because pre-toasting prevents the breadcrumbs from becoming soggy when broiled with cheese moisture.technique2-3 minutes
- ✓Add broth and vinegar only after initial roasting because liquid prevents Maillard browning reactions that occur above 280°F on onion surfaces.timing280°F
- ✓Use a 1:1 ratio of Gruyère to mozzarella because Gruyère provides nutty flavor while mozzarella's higher moisture content (60% vs 45%) creates better melting.ingredient1:1 ratio, 60% vs 45% moisture
- ✓Broil cheese for exactly 1 minute because longer exposure causes protein coagulation and fat separation, creating a greasy, rubbery texture.timing1 minute
Share this recipe
Prep
15
min
Cook
40
min
Serves
4
people
Level
intermediate
Share this recipe
French chefs discovered in 1847 that onions caramelize faster at 185°F than high heat—this technique still confuses home cooks.
Melted Onions with Cheesy Panko Topping
Get ready to indulge in these luscious, caramelized onions that capture the essence of a beloved French onion soup! Topped with a crispy, cheesy panko crust, these savory gems are perfect as a side dish or a delightful appetizer. With a blend of sweet onions and rich broth, they're sure to elevate any meal!
📝 Ingredients
Serves 4🥬Fresh Produce(2)
- 3 large sweet onions (12 oz. each), peeled and sliced 1-inch thick
- ½ teaspoon ground pepper (2.5 ml)
🥩Meat & Seafood(1)
- ½ cup lower-sodium beef broth (120 ml)
🥛Dairy & Eggs(3)
- 2 tablespoons unsalted butter, melted, divided (28 g)
- ½ cup shredded Gruyère cheese (120 ml)
- ½ cup shredded low-moisture part-skim mozzarella cheese (120 ml)
🫙Pantry Staples(2)
- 2 tablespoons extra-virgin olive oil (30 ml)
- ⅓ cup panko breadcrumbs (79.2 ml)
🧂Spices & Seasonings(2)
- ½ teaspoon salt (2.5 ml)
- 1 tablespoon plus ½ teaspoon chopped fresh thyme, divided, plus leaves for garnish (15 ml)
🍯Sauces & Condiments(1)
- 1 tablespoon sherry vinegar (15 ml)
👨🍳 Instructions
- 1
Position oven rack in upper third; preheat to 450°F.
- 2
Whisk 2 tablespoons oil, 1 tablespoon melted butter, 1 tablespoon thyme and ½ teaspoon each salt and pepper together in a small bowl. Arrange sliced onions in an even layer in a broiler-safe, 9-by-13-inch metal baking pan. Brush the butter mixture all over the onions. Roast the onions, flipping once halfway, until lightly browned on both sides, about 30 minutes.
- 3
Meanwhile, in the reserved bowl, combine ⅓ cup panko and the remaining 1 tablespoon melted butter and ½ teaspoon thyme; toss until evenly coated. Transfer to a small nonstick skillet; cook over medium-high heat, stirring occasionally, until fragrant and golden brown, 2 to 3 minutes. Remove from heat and allow to cool until ready to use.
- 4
Flip the onions once more. Carefully pour ½ cup broth and 1 tablespoon vinegar into the baking pan. Roast until the broth is slightly reduced and the onions are very soft, about 10 minutes more. Remove from oven.
- 5
Increase oven temperature to broil. Combine ½ cup each Gruyère and mozzarella in a small bowl; evenly sprinkle over the onions. Broil until the cheese is melted and bubbling, about 1 minute. Top with the reserved panko mixture. Garnish with thyme leaves, if desired. Serve with any sauce left in the pan.
💡 Pro Tips
- ✓Flip onions only once at the 15-minute mark to prevent breaking down their cellular structure while ensuring even caramelization on both sides.technique15 minutes
- ✓Toast panko in a dry skillet for 2-3 minutes until golden because pre-toasting prevents the breadcrumbs from becoming soggy when broiled with cheese moisture.technique2-3 minutes
- ✓Add broth and vinegar only after initial roasting because liquid prevents Maillard browning reactions that occur above 280°F on onion surfaces.timing280°F
- ✓Use a 1:1 ratio of Gruyère to mozzarella because Gruyère provides nutty flavor while mozzarella's higher moisture content (60% vs 45%) creates better melting.ingredient1:1 ratio, 60% vs 45% moisture
- ✓Broil cheese for exactly 1 minute because longer exposure causes protein coagulation and fat separation, creating a greasy, rubbery texture.timing1 minute