© Denzil Green
In Eastern Europe, certain types of pumpkins are grown especially for their seeds to be made into oil. The pumpkins are squished by machines right in the field, the seeds extracted, and the pumpkins discarded right back onto the fields to be used as fertilizer.
In North America, pumpkins are grown for processing into pie filling, and the seeds are the by-product. These seeds can be toasted and seasoned for eating as a snack, or used as an ingredient in cooking.
Pumpkins that have hull-less seeds have been developed for the snackseed trade. The seeds aren’t really hull-less; it’s just that the seedcoat is so thin it doesn’t need to be removed. One variety is Snack Jack Pumpkins, which consumers can buy to grow at home; another variety, termed “NH1041”, has been bred primarily for commercial use. 
Raw Pumpkin Seeds are green.
To roast, remove seeds from pumpkin flesh. Wash and remove any clinging flesh.
Some people recommend to brine the seeds overnight at this point, saying it helps particularly if the seeds aren’t hull-less; that the brining makes the seed shell easier to crack later.
Drain the seeds.
At this point, you may wish to toss them seeds in some oil and some seasoning before roasting; if so, let the seeds dry first before doing applying the oil and seasoning.
Spread the seeds out on a baking sheet and roast at 175 C (350 F) for 10 minutes, or more slowly at 120 C (250 F) for about 25 minutes, until golden brown and crisp.
Use pumpkin seeds as an out-of-hand snack food; other uses include as a topping for muesli, other cereals, yoghurt, salads, soups, in muffins, in trail mixes, or in smoothies (grind first on their own.)
Most of the fat is unsaturated. High in magnesium and zinc.
There is a growing belief among men, which is clinically unproven as yet (2012), that pumpkin seeds can help promote prostate health. “Pumpkin seed oil has become popular today as a treatment for prostate enlargement ( benign prostatic hyperplasia, or BPH), and it was approved for this use in 1985 by Germany’s Commission E. However, there is no meaningful evidence that pumpkin seed is helpful for this condition. Only double-blind, placebo-controlled studies can prove a treatment effective, and none have been reported for pumpkin seed oil alone.” 
1 cup hulled seed (i.e. just the kernels) = 140g = 5 oz by weight
 Loy, Brent J. Hull-less Seeded Pumpkins: A New Edible Snackseed Crop. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR. 1990. pp 403-407.
 Pumpkin Seed. Lahey Clinic. July 2012. Retrieved December 2012 from http://www.lahey.org/Departments_and_Locations/Departments/Cancer_Center/Ebsco_Content/Prostate_Cancer.aspx?chunkiid=111795