Remove seeds from your pumpkin and place in a colander. Place colander in your sink and rinse with water, removing as much of the stringy pumpkin guts as you can. Pour seeds on to a rimmed baking sheet and allow to dry overnight. The following day, pick out any remaining pieces of pumpkin.
Preheat oven to 325 F degrees. Spray a clean rimmed baking sheet with cooking spray.
Toss seeds in a bowl with the olive oil and garlic salt. Spread the seeds on the prepared baking sheet and bake for about 20 to 30 minutes or until golden brown, stirring about halfway through.
Taste and season with additional garlic salt if desired.