We have an abundance of wonderful fresh butter in Ireland and lots of eggs. But keeping them after the hens stopped laying was difficult till local farm women figured out how to extend the shelf life by coating newly laid eggs in butter. The butter would soften and absorb into the shell, making an airtight seal and preserving the eggs for up to six months. Nothing tastes like a poached buttered egg.
A tour guide in (unsurprisingly) Cork Butter Museum tells a Canadian journalist about our local delicacy, which I have never, ever heard of.