Drain cooked prunes, reserving 1c. liquid; pit and measure. Remove all white inner peel when peeling orange.
Combine brown sugar, salt and cornstarch. Add prune liquid and bring to a boil, stirring constantly. Cook until thick. Add prunes, orange, orange peel and butter; cook 10 minutes, stirring occasionally. Cool.
Pour into pie shell. Refrigerate until mealtime. To serve, add 2 tblsp. white sugar to whipped cream and spread on pie. To dress up pie, garnish with orange sections and a few walnut halves.