Rainbow Cake in a Jar You'll need three one-pint canning jars, vanilla frosting, sprinkles and one fresh medium-sized Nyan Cat. Follow Brooke McLay's recipe at the link and you'll have gorgeous rainbow jar cakes like this one.Link -via Karyn Regnerus Comments (1) I tried this last year... it was not a success. :( Abusive comment hidden. (Show it anyway.) Login to comment. Enable JavaScript and Click here to access all of this post's 1 comments