Carmelized Onion, Thyme, & Gruyere Paninis

I found this recipe on Good Things Catered. I needed a sandwich to make for our Asparagus Bisque that we made for dinner tonight. This sounded like a delicious addition to that dinner. And it was! Both Joel and I loved this panini. It was super simple, too. I didn't make the 6 servings that this recipe called for, so I scaled it down just to make 2 sandwiches.

1 loaf Ciabatta Bread
1/2 Sweet Onion, sliced thinly
1 tablespoon Olive Oil
1/4 teaspoon Salt
1/4 teaspoon Balsamic Vinegar
2 slices Provolone Cheese
Shredded Gruyere
Thyme (I used dried instead of fresh)

Add the oil to a frying pan and add sliced onion and salt. Cook, stirring occasionally, until the onions have become carmelized. Add a dash of balsamic vinegar to the onions and stir to mix well.
On one slice of bread, add a slice of provolone and top that with some thyme. Top with a pile of the carmelized onions, then add a handful of gruyere. Top with the slice of bread and put the sandwich into a panini press. Cook until the cheese is melted and the bread is toasted.