Spread pumpkin seeds in a single layer on a baking sheet lined with waxed paper; set aside in a cool, dry place and allow to dry overnight, turning seeds a time or two during several hours of drying.
Preheat oven to 300 degrees F (150 degrees C).
Mix melted butter, Cajun seasoning, garlic powder, paprika, chili powder, seasoned salt, and teriyaki sauce in a bowl; toss the pumpkin seeds in the seasoned butter to coat. Set seasoned pumpkin seeds aside for 5 minutes to absorb flavors. Spread seeds onto a baking sheet.
Bake in the preheated oven until seeds are browned and fragrant, 45 minutes to 1 hour; stir after 30 minutes. Remove and let cool until seeds stop making a popping noise; sprinkle with salt if desired.