unsalted butter, divided • small red potatoes from boil, coarsely chopped (~1 cup) • corn kernels from boil (cut from cob, ~1 ear) • chopped, small, sweet yellow onion from boil (may use fresh) • crawfish tail meat • creole seasoning (such as Tony chachere's), divided • large eggs • plain Greek yogurt • milk • salt, optional • shredded cheese (whatever type you prefer) • chopped fresh parsley