Rinse the pumpkin seeds and dry them on a clean kitchen towel.
Preheat your oven to 350°F. Line a large, rimmed baking sheet with parchment paper.
Place the pumpkin seeds in a medium bowl. Add the olive oil, kosher salt, smoked paprika, garlic powder, and cayenne pepper. Mix with a large spoon or your hands until the seeds are well coated.
Spread the pumpkin seeds in a single layer on the prepared baking sheet. Roast until golden for 15-20 minutes, stirring them halfway through.
Serve immediately - they are perfect when warm!
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Notes
Check the seeds after 15 minutes, and watch out to ensure they don't burn. They quickly progress from pale to brown. When done, they will have a deep golden color, very different from their white color in their raw state. Note that they should be golden, not brown. When they become dark brown, it means you over-roasted them. So keep a close eye on them!
If you're not into spicy food, simply omit the cayenne pepper. You'll get delicious, well-seasoned seeds without the heat. On the other hand, if you enjoy spicy foods, you can double the cayenne.
Storage: After you cool them completely, store these seeds on the counter in an airtight container for up to two weeks. For more extended storage or if your kitchen is hot, store them in an airtight container in the fridge for up to a month. You can reheat them in the microwave at 50% power. You can also freeze these seeds in a freezer-safe container for up to three months.