Butter a 13x9x2-inch baking pan. Set aside.
In a heavy 2-quart saucepan, combine sugar, butter, evaporated milk, pumpkin, cinnamon, ginger, and nutmeg.
Bring mixture to a boil, stirring constantly. Reduce heat. Boil over medium-low heat until mixture registers 234 degree F (soft-ball stage) on a candy thermometer, stirring constantly (about 25 minutes).
Remove from heat and stir in butterscotch pieces until melted. Add marshmallow creme, nuts and vanilla. Mix until well combined.
Pour mixture into prepared pan, spreading evenly. Cool at room temperature. Cut into squares. Wrap tightly and store in refrigerator. Makes 3-1/4 pounds.