Follow the recipe and place the little cut egg whites in a sealable container in the refrigerator. Place your pastry piping tip in a pastry bag and use a twisty tie to seal the bag just above the tip. Spoon your filling into the bag, then seal the other end as well with a twisty tie and refrigerate. When you’re ready to serve your eggs, simply take your egg whites out of their sealed container and remove the twisty-tie from the bottom of the piping bag to fill your eggs. You can make the eggs and filling a whole 24 hours ahead of time, but don’t fill them until a half hour before serving, at most! They will begin to dry out shortly after filling.