Linda from Pane, Amore e Creativita shows how she made this costume for her daughter to dress up like Anna from the movie Frozen. Her tutorial includes how to make the cloak, the bodice, and the skirt. Her blog is in Italian, but the photos alone give a good idea of what to do. You could also use a site translator to read the instructions in English. Go to Pane, Amore e Creativita for the tutorial.
[photo from Pane, Amore e Creativita]