Their is only one way to really truely solve the problem, freezer camp. You can't rehome or give away an egg eater, you can't train them not eat their eggs once they start, and that's the truth. They will teach the others to do the same if you don't rid your coop of them now. I have had several in the past years and none!!!! ever ever ever quit eating eggs. Think about it.
In the original nesting box, they could barely move around in the box. In the new boxes, they are able to move around more freely.
I did what others recommended by putting mustard, tabasco, white pepper in a half eaten egg and gave it to my Delaware and the others. They did not like my sauce.
I also put cardboard atop each nesting box, effectively making it 1-2" shorter.
Yesterday, my Delaware egg was not eaten or cracked.
I will provide updates. However, if the Delaware continues to eat the eggs, I will slope the bottom of the nest to allow it to roll away to the back. If that doesn't work, I am going to have Delaware fried chicken.