To be honest, this isn't a dead pan, but I thought it was going to be. Running for the camera may not be the best of instincts when one's burnt a pan bottom, but it didn't really seem to inflict lasting harm. But (clearly I can't get the concept out of my system) it did get me reflecting on where the term came from...
... and it's surprisingly recent: the OED gives as its first citation the NYT in 1928: "Dead pan, playing a role with expressionless face"... I like the *Tablet* (England's catholic church journal) in 1942, saying "Mr Attlee and Sir Stafford Cripps did their best to assume what in America is called a 'dead pan' expression." It seems that "pan" is a very, very old word (pann, panne, panna [I thought that was cream??] etc - turning up in what I suppose one would call a pan-European way), meaning head or skull as well as the round thing that one's cooking in. When a film camera "pans," incidentally, it's an abbreviation for acting in a panoramic way.
So. It didn't turn out, I'm afraid, to be all that interesting. But be glad to know that the spinach that then went into the slightly carbonized pan tasted fine - just a little smoky - after it was cooked with oil, chopped onions, garlic, cumin, and lemon juice.