Combine water, pumpkin seeds, and salt together in a pot; bring to a boil, reduce heat to low, and simmer until seeds are tender, about 10 minutes. Strain seeds, discarding water, and lightly pat seeds dry with a towel.
Preheat oven to 325 degrees F (165 degrees C). Lightly oil a baking sheet with olive oil.
Spread pumpkin seeds out in a single layer on the prepared baking sheet. Sprinkle sugar, cinnamon, and ginger evenly over seeds.
Bake in the preheated oven, stirring every ten minutes, until seeds are fragrant and roasted, about 40 minutes.