This updated egg salad uses fewer yolks, forgoes mayo, and takes on watercress and whole-grain bread for the sandwich.
Prepare an ice-water bath; set aside. Cover eggs with 1 inch of cold water in a large saucepan. Bring to a boil. Remove from heat; cover, and let stand 11 to 12 minutes. Transfer eggs to ice-water bath; let stand 2 minutes. Peel eggs; cut in half, and remove yolks. Crumble 2 yolks, and set aside; discard remaining yolks. Finely chop egg whites, and transfer to a medium bowl. Add crumbled egg yolks.
Whisk together ricotta, yogurt, mustard, chives, and salt in a small bowl; season with pepper. Add to egg mixture, and gently stir to combine.
Arrange egg salad, then watercress, over 4 slices of bread, dividing evenly. Top with remaining slices of bread.