Line a 13x9x2-inch baking pan with foil, extending foil over edges of pan. Butter foil; set pan aside.
In a 3-quart heavy saucepan combine sugar, butter, evaporated milk, and pumpkin. Cook and stir over medium-high heat until mixture boils. Clip a candy thermometer to side of pan. Reduce heat to medium-low; continue boiling at a moderate, steady rate, stirring frequently, until thermometer registers 234 degrees F, soft-ball stage (20 to 25 minutes). (Adjust heat as necessary to maintain a steady boil.).
Remove saucepan from heat; remove thermometer from saucepan. Stir in cinnamon-flavored pieces until melted. Stir in marshmallow creme and walnuts.
Immediately spread fudge evenly in prepared pan. Score into squares while warm. Let fudge cool to room temperature (about 2 hours). When fudge is firm, use foil to lift it out of pan. Cut into squares. Cover tightly and chill for up to 1 week. Do not freeze. Makes about 96 pieces.