Cut the top or bottom off of the pumpkins using a sharp kitchen knife or a serrated knife meant for cutting pumpkins.
Use the flat edge of a sturdy spoon or spatula to scrape the pulp away from the pumpkin.
Scoop out the pumpkin seeds leaving behind as much of the pulp as possible.
Put the seeds (and any of the pulp still sticking to them) into a large colander. Put the colander in an empty sink under running water. While rinsing the seeds, separate the pulp from the seeds and remove it.
Pour the seeds into a large pot. Add water and salt. Bring to a boil over medium heat. Turn heat to low and simmer for 10 minutes. Drain well before roasting.
Put the drained pumpkin seeds into a bowl. Stir in olive oil and seasoning or spices of choice.
Pour into a foil-lined rimmed baking sheet. When roasting pumpkin seeds of more than one flavor, use aluminum foil to make divided sections in a large rimmed baking sheet. Put one flavor in each section.
Bake the pumpkin seeds at 375˚F for 25-30 minutes, stirring and turning the seeds every 5 minutes, until golden and crunchy.
Store in an airtight container or ziptop bag at room temperature or in the refrigerator.