Looking for ideas on what to use as "artichoke dip" that gets dumped on an actor's head. The director wants realistic  (as opposed to handling it in a non-messy way with a duplicate permanently gooped up costume.  Ha! Wouldn't that have made my life easier!), and the actor is game for anything (love her!). The dumping occurs off-stage with the actor presenting the results onstage. It also happens at the end of the play, so mess isn't too much of a concern (it'll just become part of post-show cleanup). Having said that, though, I'd love to keep the mess contained to the actor rather than have it drip all over the floor, if possible.  Any ideas?

One possibility you might try is to prepare a artichoke dip hat of sorts.  You could do this much like taking a life mask with plaster of paris.  Cover her head with plastic wrap (leave holes for breathing) then pour the partially hardened plaster on top of her head.  Put a bowl in the plaster so that it hardenens into place.  Once it hardens, slip it off her head, paint it to look like dip and bingo artichoke dip hat.

New here, so bear with me 8)
I had to come up with "quick drying plaster" for Bugsy Malone, and found that Corn Flour (Corn Starch if you're in the US) mixed with water makes a very white, very plastery, very CLEANABLE "plaster". In my experimenting, using icing sugar (powdered sugar) gave a similar consistency, but with less opacity. The problem would be if you're concerned about costumes/wigs, as it'll be sticky.