Caramelized Onion Grilled Cheese

In a cast iron pan, heat olive oil over medium heat. Add finely sliced onions and saute for 5 minutes until translucent. Reduce the heat to low and continue to saute for 20 minutes allowing onions to caramelize.

Once onions are golden brown, season with salt & pepper to taste and add the Caramelized Onion Balsamic Vinegar. Stir for 1-2 mins, and set aside in a bowl. 

Preheat oven to 350 degrees. Meanwhile, take a bread slice and layer a base of Gruyere, generously spread caramelized onions, sprinkle thyme leaves, and top off with another layer of Gruyere. Seal the sandwich with a bread slice. 

In a clean skillet, drizzle extra virgin olive oil and heat it over medium-low heat. Place the sandwich in the skillet and toast. Once both sides are golden transfer to oven until cheese is melted to perfection.