Combine marshmallows, pumpkin and seasonings in top of double boiler.
Heat over boiling water until marshmallows are melted; cool.
Combine milk pow- der and 1/2 cup cold water; chill until icy crystals form.
Whip milk mixture until stiff.
Fold in pump- kin mixture.
Turn filling into pie shell; chill well.
Garnish with pecan halves.