See my Hokkaido Milk Sandwich Loaf recipe for Step by Step directions.
Cut dough into 15 even pieces.
Using your palms, roll dough to 7 inches long.
Place each piece of dough on a cookie sheet, one inch from each other. Flatten dough with your palms.
Cover dough and place in draft free area. Allow to rise 5 hours.
Bake at 350 degrees for 15 minutes, or until lightly browned.
Remove from oven and brush with melted butter.
Place on wire rack and cool.
The Egg Whites yield a very fluffy texture. If you want to substitute some of the total weight with just one yolk, that will work, but the bread will be a bit chewy...Just a bit. I do this sometimes when I don't want to waste so many yolks.