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Ingredients
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For the Croques
For the Caramelized Sweet Onion
Method
For the Caramelized Sweet Onion
Caramelize the Onions
Lower the heat and cook the onions for an additional 20-25 minutes, stirring frequently, until they are golden brown and caramelized. Add balsamic vinegar and fresh thyme, stir well, and cook for another 2 minutes. Remove from heat and set aside.
For the Croques
Assemble the Croques
Preheat a skillet over medium heat. Brush one side of each slice of sourdough bread with truffle oil. Place two slices, oiled side down, in the skillet. Layer with Gruyère and Fontina cheese, followed by a generous amount of the caramelized sweet onion. Top each with another slice of sourdough, oiled side up.