Preheat oven to 450F. Prick pastry shell; bake at 450F for 9 to ll minutes, Remove from oven. Let cool.
Beat egg whites and cream of tartar at high speed for 1 minute. Slowly add 1/2 cup sugar until peaks form. Set aside.
Combine cubed cantaloupe, egg yolks, sugar, milk, salt, and cornstarch in blender and mix completely. Cook in 2-quart heavy sauce pan over medium heat, stirring constantly until thick and bubbly. Stir in vanilla and margarine. Pour into prepared shell and spread meringue, sealing edges. Bake at 400F until brown. Cool or put in fridge until cold.
Cajun Country -- New Iberia, Louisiana