Clean pumpkin seeds of any pumpkin pulp and rinse. Fill a bowl with lightly salted water and soak the pumpkin seeds for 2 hours.
Preheat oven to 300 degrees F (150 degrees C). Line a baking sheet with nonstick aluminum foil (such as Reynolds(R)).
Drain seeds and pat dry with paper towels. Mix melted butter, Worcestershire sauce, salt, and garlic powder in a bowl, and toss the seeds in the seasoned butter mixture until coated. Spread seeds out onto the prepared baking sheet in a single layer.
Bake in the preheated oven until seeds are crunchy and golden brown, about 1 hour; stir and turn seeds every 15 minutes.