When my grandparents were living in the country the electric company had a little monthly 'magazine' and people would request recipes. One woman asked if anyone knew how to make Egg Butter. Her parents used to make it but she hadn't ever learned how and her folks had passed on.
My grandmother wrote how to make it and mailed it to the woman. She never heard back if that was what she was looking for.
I asked my grandmother what it was and what it was used for. She said it was a way to use up extra eggs and butter. Her family used it on pancakes, toast and other things.
Pretty simple actually.
Hard boil eggs, cube butter. Peel eggs, chop eggs, mash eggs, add the cubes of butter mash together until creamy, add salt and pepper if desired.