The Happy Gilmore and Click star will play a stressed out real estate developer who receives a shock when the elaborate bedtime tales he regales his niece and nephew with begin to come true, according to Hollywood Reporter.
Recently entering fatherhood for the first time is said to have convinced Sandler to join the cast: the actor will also have some creative control over the film, as he's also producing it alongside regular collaborator Jack Giarraputo.
"The fact that he is a new father, and the idea of making a beautiful Disney-brand fantasy is something that is in his heart right now," said director Adam Shankman.
"And he gets to play dual roles. He gets to play a regular guy and a knight in shining armour in the fantasy world. The comedic possibilities are limitless. And there is nothing better than Adam and kids. It's going to be really fun."
Production will start this year for a Christmas 2008 release.