Ingredients

• 2 tablespoons salted butter
• 1 tablespoon extra virgin olive oil or salted butter
• 2 large white onions thinly sliced
• 2 large yellow onions thinly sliced
• 2 tablespoons Worcestershire sauce
• 2 teaspoons spicy brown mustard
• 1 teaspoon Italian seasoning
• ½ teaspoon garlic powder
• 1 teaspoon granulated sugar helps with the caramelization, optional
• ½ teaspoon fresh ground black pepper
• ½ teaspoon fine sea salt
• 6 slices bread French, sourdough, brioche, etc.
• 3 tablespoons mayonnaise optional, for spreading onto the bread
• 6 slices Provolone cheese
• 6 slices Gruyere cheese

Directions

• Heat butter and extra virgin olive oil in a large skillet over medium heat.
• Add the sliced onions, Worcestershire sauce, spicy brown mustard, Italian seasoning, garlic powder, sugar if using, black pepper and salt. Stir to combine.
• Cook, stirring occasionally, until the onions are golden brown and caramelized about 20–25 minutes. Cook until the liquid evaporates. Set aside.
• Heat a clean skillet over medium heat.
• Spread mayonnaise on one side of each bread slice optional, for extra crispiness.
• Place bread in skillet, mayonnaise side down.
• Top with slices of Provolone, followed by the caramelized onions and finish with Gruyère.
• Top with another slice of bread mayo side facing out.
• Cook until the bread is golden brown and crispy, and the cheese is melted, about 2-3 minutes per side.
• Slice in half and serve immediately with your favorite chips.

Photos