Roast the Pumpkins. Set cleaned pumpkin halves on a lightly oiled baking sheet. Roast in a preheated 375°F oven (the temperature is actually quite flexibly – anywhere in the 350-425 range will yield results) until tender enough to pierce easily with a fork through the shell, about an hour.Scooping Roasted Pumpkin.oast the Pumpkins. Set cleaned pumpkin halves on a lightly oiled baking sheet. Roast in a preheated 375°F oven (the temperature is actually quite flexibly – anywhere in the 350-425 range will yield results) until tender enough to pierce easily with a fork through the shell, about an hour. Scooping Roasted Pumpkin.