Mix the sugar, flour and salt in a heavy-bottomed saucepan.
Gradually add the milk, stirring until well combined.
Beat the yolks and add to the pan. Mix together.
Add the butter. Over medium heat, cook the mixture and stir constantly to prevent sticking to the pan. The mixture will begin to thicken. Continue cooking until it is the consistency of pudding.
Remove form heat. Stir in the vanilla. Stir in the coconut.
Pour into the pre-baked pie crust.
In a heavy-bottomed saucepan set over medium heat, add the sugar and water. Stir to combine. Cook until the mixture reaches 240ºF.
Meanwhile, in an electric stand mixer fitted with a whisk attachment, add the egg whites. Beat until frothy, add the cream of tartar, continue beating until the mixture reaches soft peaks, being careful not to over beat until the white are dry.
Continue beating the egg whites, gradually add the cooked simple syrup, beat until the meringue is thick and creamy.
Spread the meringue on top of the coconut cream filling. Spread to the outer edges. With the back of a spoon, form decorative peaks.
With a kitchen torch, apply the flame until the meringue starts to turn golden brown.