Unlike the previous hamburger pumpkin we posted about, Joe's double cheeseburger pumpkin on Flickr is made from three pumpkins and, aside from the wrappers and containers, is 100% pumpkin! He explains,

The two patties are ground pumpkin flesh, blowtorched to brown; the fries, cheese and bun are unadulterated pumpkin; the bacon, pickle chips and spears, and ketchup are all pumpkin colored with food coloring; the tomato slices are sliced from a small, decorative pumpkin; also included is pumpkin juice from the guts and the flesh; the bun is pretty self explanatory with pumpkin "sesame" seeds.

The pumpkin juice is a nice touch. You can see the "making of" photos in his photostream.