In a medium pot, bring milk, sugar, and salt to a simmer.
Slowly add in the flour, whisking as you sparkle flour over the top of the milk.
In a medium bowl whisk together the egg yolks. Add 1/4 cup of the milk mixture to the yolks and whisk. Do this 2 more times adding 1/4 cup of the hot mixture to the eggs at a time. Once yolks are tempered (brought up to temperature but not scrambled) add them back into the pot over medium low heat. Stir constantly until the custard is thick (5-10 min).
Stir in the 1/2 teaspoon of vanilla, butter and flaked coconut (3/4 cup).
Remove from heat, stirring occasionally until cooled.
Meanwhile, whip up the cream in a stand mixer. Once soft peaks have formed in the cream add the sugar and continuing whisking until stiff peaks.
Pour cooled coconut cream in to the pre-baked pie shell. Top with whipped cream and sprinkle with toasted coconut.