For the shortcrust:
1) All ingredients should be cold. Combine all the dry ingredients in a large mixing bowl. Add shortening and butter. Using a pastry blender, cut in the shortening and butter until the mixture resembles course meal. Drop by drop, add the cold water. Mix in with the fingertips, not hands, as the palms will warm the dough. Continue mixing water in until the dough begins to hold together without being sticky but not crumbly. Lightly spray a deep 23cm pie pan or fluted flan pan. Roll out dough and place in pie pan, allowing the excess pastry to hang over the edge. Chill in the freezer for 10 mins.
2) Line the pastry shell with parchment and baking beans or beads. Bake the shell for 10 mins. Remove the paper and beans/beads and return to the oven for 10 more mins. Cool. Makes shortcrust for 23cm single-crust pie.
For the filling:
1) Lightly toast 75g dessicated coconut in oven, about 7 mins. Remove and cool. Set aside. Combine egg yolks and sugar. Beat with electric mixer until pale yellow and fluffy. Add cornflour and melted butter. Blend well and set aside. Heat milk but do not boil. Stir in coconut cream. Gradually add egg and cornflour mixture, stirring constantly over medium-low heat until filling begins to thicken. Add 1 tsp vanilla.
2) Remove filling from heat and let cool. In a mixing bowl, whisk or beat 240ml double cream on high until it begins to thicken and forms stiff peaks. Set aside. Strain cooled filling through fine mesh sieve to remove lumps. Fold in whipped cream and 75g dessicated coconut with pie filling and pour into prepared shortcrust. Whisk or beat remaining double cream on high until it begins to thicken. Gradually add icing sugar and remaining tsp of vanilla. Continue until stiff peaks form. Fold in toasted coconut and spread over top of pie. Refrigerate until mixture has cooled and set.