Preheat oven to 350°F / 177°C / Gas mark 4.
Slice a 5 - 6 lb. Hubbard squash in half with a sharp chef's knife. Use a large spoon to scrape the stringy fibers from the middle of the squash. Remove seeds and discard fibers.
Wash Hubbard squash seeds in colander or strainer to remove pulp, stirring them around with your hand to make sure they are all washed clean.
Place on clean kitchen towel and dry thoroughly.
In a small bowl, toss squash seeds with oil, salt, garlic, onion, paprika and pepper.
Place on sheet pan and roast for 15 minutes, stirring every 5 minutes to ensure even browning. *If you hear seeds beginning to pop in oven, that's your cue to remove them and check for doneness.
Cool seeds completely before storing in an airtight container.