In a large pot, combine butter, evaporated milk, sugar, pumpkin and spices.
Cook over high heat, stirring continuously until the mixture reaches 234 degrees (use a candy thermometer to keep track of the temperature). Remove from heat.
Stir in white chips until they are completely melted.
Stir in marshmallow cream until it is completely mixed in.
Fold in nuts.
Pour into a greased pan and cool in the refrigerator for 2 hours or until firm.