Apart from the name, Donkeyskin sounds exactly like something Disney would adapt into an animated feature. It's a rags-to-riches story about a runaway princess, complete with handsome prince and happy ending. The only real obstacle is the part with all the incest.
Our story begins with a prosperous royal family. The king in particular was feeling pretty good about his lot in life, what with his beautiful spouse, a loving daughter and -- no joke -- a donkey that pooped gold. But as they say, nothing donkeyshit can stay, and one day the queen fell suddenly ill. The sickly monarch told the king that, if he should ever find a woman as smokin' hot and wicked smart as she, he should marry her immediately so the royal bloodline could continue. Unfazed by the unreasonable and downright vindictive deathbed demand, the king started the hunt for his wife's replacement soon after her death.
Though he searched high and low, the widowed king could find no woman quite so bangin' as his lost love. No woman, that is, except his daughter.
Faced with the prospect of forcing his child into a life of incest or breaking an abhorrent promise he made to a dying woman that was possibly hysterical from illness, the king decided that he should probs marry his own daughter. She was understandably more than a little skeeved out about the situation. The princess consulted her fairy godmother, who apparently was out of town when this girl's mom was dying. Ol' FG recommended that the princess declare impossible requirements be met before the marriage could go forward. In particular, the princess requested three dresses of divine quality -- one the color of the sun, another the color of the moon and the last the color of the sky. She topped off the demands with the skinning of that magical gold-shitting donkey, just for kicks.
Much to the princess' surprise, the king had no problem fulfilling her wish for a yellow dress, a white dress and a blue dress. Even skinning a magical problem proved no problem for His Majesty King Creepazoid. Terrified at the prospect of her future life in the palace, which involved -- and I cannot stress this enough -- fucking her own father and having his children, the princess fled the castle. She used the donkey skin as a disguise, figuring that anyone who saw such a sight would mistake her for a crazy uggo that was a little too into the movie Freddy Got Fingered.
The newly-christened Donkeyskin toils in bakery peasant obscurity, making sure to play a game-of private dress-up with the dresses she stole before ditching the castle. It was only a matter of time before a handsome prince caught a peek, mired her self-mirin', and vowed to wed this girl by virtue of (what else) looks alone. To be fair, Donkeyskin was ironically just as superficial, because the feeling was mutual.
The prince requests that Donkeyskin make him a cake at the bakery, and in the process of doing so, she slips one of her fancy princess rings into the batter. Her plan worked, at least somewhat, as the prince totally flipped out and declared that he would marry whoever so fit the ring -- instead of you know, going directly to the girl he saw and getting down on one knee.
The Cinderella scam works anyway, as the ring fits Donkeyskin and the two are promptly married. Her father comes to his senses and apologizes, and everyone lives happily ever after... with the nagging feeling that the king probably still wants to bang his daughter.