Sorry if you’ve heard this before, but getting the pan hot is important. If the egg is cooked before it gets into the texture, it won’t stick at all. It’s tempting to add the eggs early because cast iron takes so long to heat up, but a cool pan will stick a lot more. I usually let the butter brown heavily before I crack the eggs. If you think that leaves the top undercooked, add a spoon of water and cover the pan to steam the egg tops.
Sorry if you’ve heard this before, but getting the pan hot is important. If the egg is cooked before it gets into the texture, it won’t stick at all. It’s tempting to add the eggs early because cast iron takes so long to heat up, but a cool pan will stick a lot more. I usually let the butter brown heavily before I crack the eggs. If you think that leaves the top undercooked, add a spoon of water and cover the pan to steam the egg tops.