Cook the 6 slices bacon in a skillet over medium heat, turning occasionally, until crispy and golden, about 6–8 minutes. Transfer to a paper towel-lined plate to drain. Once cool enough to handle, break or cut each strip in half.

While the bacon cooks, toast all 6 slices of slices sandwich bread white in a toaster oven until golden and crisp.

In a small mixing bowl, stir together the 4 tbsp mayonnaise and 1 tsp Dijon mustard (if using). Season with a pinch 1 pinch salt and 1 pinch black pepper freshly ground.

Lay all 6 toasted slices of slices sandwich bread white on your cutting board. Spread the mayo mixture evenly on one side of each slice.

Build the first layer: On the first slice of slices sandwich bread white (mayo side up), layer half the sliced turkey breast deli-sliced, a slice of slices Swiss or cheddar cheese optional but recommended if using, and 2 slices tomato ripe slices. Season the tomato lightly with 1 pinch salt and 1 pinch black pepper freshly ground. Top with a 4 pieces romaine or iceberg lettuce leaves torn to fit bread leaf.

Place the second slice of slices sandwich bread white mayo-side UP on top of the first layer. This is the middle slice. Add the remaining sliced turkey breast deli-sliced, 3 strips of slices bacon (halved), and another 4 pieces romaine or iceberg lettuce leaves torn to fit bread leaf.

Place the third slice of slices sandwich bread white mayo-side DOWN to close the sandwich. Press down gently but firmly with your palm to compact the layers slightly.

Insert a frilly toothpick into each of the four corners of the sandwich to hold it together. Using a sharp serrated knife, cut the sandwich diagonally into 4 triangles (cut corner to corner in an X pattern). Repeat to build the second sandwich.

Serve immediately with chips, a dill pickle spear, or a simple side salad.