WARNING: more unsolicited advice ahead.
Did she break open the egg herself? Once a chicken starts eating eggs, it can be very hard to stop and turns into a very destructive habit. If you opened it and gave it to her that's fine, but if she's started eating eggs on her own, she should be discouraged. The best advice I've heard for this is to populate the nests with hard (solid) fake eggs. Then when she gives one a good hard peck it will hurt and may stop her. You need lots of fake ones to increase the chances that she'll attack one of those rather than a real one. I know folks who will cull an egg eater. The others will learn and pick up the habit. Egg count goes waaaay down.