These melt-in-your-mouth onions have all the flavors of a classic French onion soup.
Brush the butter mixture all over the onions.
Do not wipe out the bowl; set aside.
Robby Lozano
Roast the onions, flipping once halfway, until lightly browned on both sides, about 30 minutes.
Remove from heat and allow to cool until ready to use.
Flip the onions once more.
Robby Lozano
Carefully pour 12 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.
Increase oven temperature to broil.
Robby Lozano
Combine 12 cup each Gruyere 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.
Robby Lozano
Garnish with thyme leaves, if desired.
Serve with any sauce left in the pan.
- Daily Values (DVs) are the recommended amounts of nutrients to consume each day.
Robby Lozano
(-) Information is not currently available for this nutrient.
