Meals in Cinderella Castle are so magical, Leslie!  Getting there from Disney's Animal Kingdom shouldn't be too much trouble.  You're going to want to take a bus to the Transportation and Ticket Center.  From there, hop on the monorail and it will deliver you right to the gates of the Magic Kingdom.  While the actual transportation should take about forty-five minutes, if it were me, I'd allow closer to ninety minutes so as to account for time waiting for the bus and making my way through the Magic Kingdom.  I certainly wouldn't want you to be late for your magical meal.  Have a regal time!