Preheat the oven to 350°F (177°C) and line a rimmed baking sheet with parchment paper.
Rinse the pumpkin seeds in a colander under cold water and remove any pulp or strings.
Place the seeds in a bowl of water, allowing the seeds to float while any remaining pulp sinks to the bottom.
Remove the seeds from the water, and boil them in salted water for 5 minutes to season and loosen any remaining pulp.
Drain the seeds and pat them dry with paper towels to remove excess moisture thoroughly.
Spread the dry seeds out in a single layer on the prepared baking sheet.
Drizzle the olive oil over the seeds, and sprinkle with kosher salt, garlic powder, paprika, and black pepper.
Roast the seeds in the preheated oven for 10-15 minutes, stirring every 5 minutes, until they are golden brown and fragrant.
Remove the seeds from the oven, and let them cool completely on the baking sheet before serving.