if you KNOW what hen did it,, you need to STOP her NOW before she shows others how to do it... or you will have the whole flock doing it
#1 pick up the eggs at least 2Xs a day (more if possible)
#2 put fake eggs in the nesting boxes (wood, ceramic or plastic)
#3 some people put curtians up (i never have)
#4 make sure their DIET is correct.. could be nutritional..
#5 give them lots of other things to peck at.. could be bordom..
#6 cut just the TIP off of the top part of the beak,, might bleed a tiny bit.. if you dont use heat to stop the bleeding the beak WILL grown back.. but it stops mine from using their sharp beaks to break the eggs.. i do this, it is better than culling them.. at first at least, gives them a second chance...
if you cant stop her you need to CULL her.. NOW...
sorry