Egg eating is one of the hardest behaviors to modify once it starts. First increase the protein in her food because she may have a deficiency. I used fake wooden eggs in my nesting boxes when I had problems with chickens pecking at their eggs. A few pecks at the solid wood and they stopped pretty quickly. I have also heard of people using plaster eggs. I will say that mine never graduated to actually eating eggs. I caught them before they actually ate their eggs so the habit was easy to break. Yours will be tougher. There are some nesting box designs that enable a freshly laid egg to roll out of the reach of the chickens to protect the eggs from getting eaten. I don't know anything about those, but I read about them here so a search through the archives may give you some info.
Good luck.