Place the softened vanilla ice cream in a large bowl and set aside.
Mix remaining ingredients (in a different bowl) with an electric mixer on low speed. Blend into ice cream with a spoon. Stir until all ingredients are mixed together.
Spread ice cream/pumpkin mixture in a 9" x 13" pan. Cover, and freeze. It takes a long time to get it fully frozen, so I'd make it the day before if you're planning it for a special occasion.
Let soften slightly before scooping and serving. Makes about 8 servings.