01 - Evenly toast all bread slices in a toaster until golden brown and crisp.
02 - Cook bacon strips in a skillet over medium heat until thoroughly crisp. Transfer to paper towels to drain excess fat.
03 - Using a knife, evenly spread a thin layer of mayonnaise on one side of each toasted bread slice.
04 - On one bread slice, arrange half the romaine leaves, half the tomato slices, and two chicken breast slices. Lightly season with salt and freshly ground black pepper.
05 - Place a second bread slice on top, mayonnaise side down. Spread mayonnaise on the exposed top side.
06 - Layer two bacon slices, remaining chicken, lettuce, and tomato on the second bread slice.
07 - Complete with the final bread slice, mayonnaise side down. Gently press the sandwich together.
08 - Insert toothpicks into each half of the sandwich to secure. Cut diagonally into quarters using a sharp knife.
09 - Serve immediately for optimal freshness and texture.