Place the bread slices in a toaster or pan and toast them lightly until they turn golden. Keep the inside soft and do not over toast.

Lay the toasted bread slices on a clean surface. Spread mayonnaise evenly on one side of each slice. Add a thin layer of mustard if using.

Take one slice of bread and place lettuce leaves on top. Add sliced chicken or turkey evenly, then place tomato slices over it. Sprinkle a little salt and pepper.

Place the second slice of bread on top of the first layer and press gently. Add the cheese slice, then place the cooked beef bacon evenly over the cheese.

Cover with the third slice of bread. Press lightly from the top so the sandwich holds together without losing its shape.

Use a sharp knife to cut the sandwich into triangles. Cut slowly to keep the layers neat. Insert toothpicks if needed to hold the sandwich together.

Serve immediately while fresh for the best taste and texture.