In a large bowl, whisk together all ingredients, until the sugar is dissolved.
Pour pumpkin mixture into an ice cream maker and churn according to the manufacturer's directions. (I have a Krups ice cream machine and it took about 30 minutes to reach soft serve.)
If you like soft serve, eat it right away. Otherwise, transfer to a container and freeze for a couple of hours to firm up. The ice cream may be quite hard when you first take it out of the freezer, so you may want to let it sit a few minutes to soften before trying to scoop. Makes 1 quart.