To make the Salmon Filling, combine all of the ingredients in a 1-quart bowl until blended. Cover and chill for at least 1 hour.
To make the Blue Cheese Filling, combine all of the ingredients in a 1-quart bowl until blended. Cover and chill for at least 1 hour.
To make the Egg Filling, press the hard-boiled eggs through a sieve, and place the sieved eggs in a 1-quart bowl. Add the remaining ingredients, and combine until blended. Cover and chill for at least 1 hour.
To make the topping, combine all of the ingredients in a 1-quart bowl until blended. Set aside.
Using a large serrated knife, trim the crusts from the bread. Carefully cut the loaf lengthwise into 4 equal-sized horizontal slices.
Line a serving platter with the lettuce leaves. Place 1 of the bread slices on the lettuce, and spread with the Salmon Filling. Top with another bread slice, and spread with the Blue Cheese Filling. Top with a third bread slice, and spread with the Egg Filling. Top with the remaining slice of bread.
Using a large knife, spread the topping over the top and all 4 sides of the sandwich stack. Sprinkle the chopped sprouts over the topping, and arrange the tomatoes and olives in a decorative pattern over the sprouts. Serve immediately, slicing each serving as needed.