Scary egg-eater has called my bluff

[Masonjars]

You can try an all flock feed. It generally has higher protein, but less calcium, so the oyster shell on the side is a must. The thing about oyster shell is they seek it out when they need it. Sometimes mine is gone in a flash and other times, they are barely touching it. It doesn't cost anything for it to sit in a dish. The calcium should always be offered as a supplement not mixed into feed or water - unless you are treating a single hen for egg laying issues then you try different remedies.

As far as eliminating competition, I doubt it. We are always trying to give human qualities to animals. It's more likely that since the whole egg is gone she's lacking nutrients.
Have you caught her eating the egg? Not just eating a broken egg (all chickens will eat a broken egg given the chance), but literally breaking it on purpose and eating it?

The other thing to look at is the treats you're offering. Are you offering too much that it's diluting the nutritional value of the feed?

She always comes into the coop while I’m collecting eggs and starts attacking whole ones. She must do it some other times too, since I see the remains of shells or yolk laying around on the bedding, but it’s gotten so bad that I have to close the coop door first so she can’t get in and then collect the eggs. The others just pick at the shell if they see it, they’re not going after whole eggs.

For your other question (thank you for all the help!), the only treats they get are the occasional wild strawberry or bell pepper top, but it’s on the order of once per week. They get basically all their nutrition from the food and whatever insects they eat that wander into the run.

 

[Crazy Maizie]

Can you try a roll away nest box?

 

[Masonjars]

Can you try a roll away nest box?

Only once they get a bigger coop…I have plans for that, but life hasn’t cooperated yet