01 - In a skillet set over medium heat, cook the bacon strips until crisp. Transfer to a paper towel-lined plate to drain excess fat.
02 - Spread softened butter evenly on one side of each bread slice.
03 - On the unbuttered side of two bread slices, arrange half the cheddar cheese, a layer of apple slices, and two bacon strips on each. If desired, add a light spread of honey or Dijon mustard. Top with remaining bread slices, buttered side facing outward.
04 - Preheat a skillet or griddle over medium-low heat. Place assembled sandwiches in the pan. Cook for 3–4 minutes per side, pressing gently with a spatula, until bread is golden and cheese is melted.
05 - Remove sandwiches from the skillet. Let stand briefly before slicing and serving warm.