Pumpkin Pie Smoothie

1 (15 ounce) can pure pumpkin, chilled
1 (12 ounce) can evaporated milk, chilled
1 cup (8 ounce container) vanilla low fat yogurt
1/4 cup granulated sugar
1/4 teaspoon pumpkin pie spice
Whipped cream or Cool Whip

Combine all ingredients except whipped topping. Blend well. Top with whipped topping and a pinch of pumpkin pie spice.