1pre make graham cracker crust and set aside in fridge to reform.
2in sauce pan add sugar cornstarch water and lime juice and coconut milk. mix together well and turn heat to medium heat. stiring constantly until mixture thickens, turn down heat to low and add butter, stir for one minute. turn off heat and let butter melt into mixture. add zest. set aside and cool for five minutes. spoon into graham cracker crust and refridge for about 1 hour. or until set and cool.
3In mixing bowl with whisk attachment add heavy whipping cream and whip for about 5 minutes or until it starts to thicken, add vanilla, and 1/2 of the powdered sugar, mixing for 5 minutes add remaining powdered sugar. whip until very light and fluffy.(almost a merringue consistency). pipe onto pie and sprinkle toasted coconut flakes.
I let my pie sit in fridge for another 15 minutes. and then serve. it serves 6