Preheat your air fryer to 375 degrees Fahrenheit (190 °C)
Spread a thin layer of butter on one side of each slice of bread. (Picture 1)
Sprinkle garlic powder, thyme and Italian seasoning on each buttered side. (Picture 1)
Place the bread slices, butter-side down, in the air fryer basket. (Picture 2.)
Top each slice with cheese, 2 tablespoons of caramelized onions, and another slice of cheese. (Pictures 3 and 4)
Cook for 6-8 minutes or until the cheese is melted and bubbly and the sandwich is golden brown. Be sure to flip halfway. (Pictures 5 and 6)
Serve hot and enjoy!
