I heard raw, but I don't know if it is true or not. I usually just hurl a pumpkin in the run and stand back. They will eat it down to the skin in a matter of days. The "guts" are gone almost instantly.
Feed it raw, cooking them cooks out some of the benefits.
The best way is to crush or chop them up, then feed it. And if you have the resources available, mixing in some chopped up watermelon or cucumber seeds also works.
Pumpkin seeds DO kill parasites, they contain a chemical that paralyzes them. Look it up.