Remove all the pulp and strings from the pumpkin seeds, then wash and thoroughly dry the seeds.
Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment paper.
Place the melted butter in a bowl, toss the seeds in the butter to coat, and pour them onto the prepared baking sheet. Sprinkle about 2 tablespoons of sugar and 1 teaspoon cinnamon over the seeds, stir the seeds around to mix the coating, and spread them into a single layer. Bake the seeds in the preheated oven for 5 minutes.
Remove the seeds from the oven, and sprinkle them with another coating of 2 tablespoons sugar and 1 teaspoon cinnamon, mixing the seeds together and spreading them out as before. Bake 5 more minutes. Repeat the coating and baking step one more time, and bake the seeds for 5 more minutes.
Sprinkle the seeds with the remaining 2 tablespoons of sugar, mix, and bake the sugar coating onto the seeds, about 10 more minutes. Let the seeds cool on the baking sheet before eating.
