If you can't get mascarpone cheese, you can substitute 4 ounces of cream cheese, 1/8 cup sour cream, and 1 tablespoon heavy whipping cream blended together until smooth.
Avoid using an electric mixer, because it could give your pie a gluey texture.
You can boil the pumpkin if you prefer. Remove the top, scoop out seeds. Peel pumpkin and cut into 1/2-inch chunks. Boil in a saucepan over medium heat until pumpkin is soft. You can also bake the whole pumpkin overnight; wrap it in aluminum foil, cook it at 200 degrees F for about 8 hours, then scoop out meat and separate seeds.