I know you've seen a thousand pumpkins (sigh), but if you just joined the cookie blogging world, mine may be the first you've seen--not likely, but maybe :)
First, trace with a food writer
Black is dark. It's hard to get it without tasting like...ummm medicine, maybe? So...Start coloring with chocolate cocoa, then add your favorite black. After a little bit, flood the face. Let it dry...completely, so the black won't bleed.
Now outline the pumpkin. Let that dry a bit and flood with orange.
Go back over your orange with detail.
Add some dimples...my, he needs an eyeball!
Outline your stem, flood, wait for that to dry and add some vines If you want, add a leaf or two.