01 -
In a skillet over medium heat, cook the turkey bacon until crisp. Transfer to a plate lined with paper towels to drain.
02 -
In the same skillet, melt 1 tablespoon of butter over medium-low heat. Add the sliced onion and cook, stirring frequently, for 15 to 20 minutes until onions are golden and tender. Optionally, add a pinch of sugar to enhance caramelization. Once done, set onions aside.
03 -
Arrange 4 bread slices on a clean work surface. Top each with 1 slice of cheese, 2 slices of cooked turkey bacon, a spoonful of caramelized onions, and another slice of cheese. Cap with the remaining bread slices.
04 -
Preheat a clean skillet or griddle over medium heat. Spread butter evenly on the exterior of each sandwich. Place sandwiches in the skillet and grill for 2 to 3 minutes per side, pressing gently with a spatula, until the bread is golden brown and cheese has melted.
05 -
Slice sandwiches in half and serve immediately, ideally accompanied by chips, soup, or a crisp salad.