In a medium saucepan, bring 1 3/4 Cup water to boil. In a separate bowl, mix the dry ingredients together. Beat the dry ingredients into the boiling water and stir until well blended. In a separate small bowl, beat egg and add some of the hot mixture to the egg, beating well. Add the egg mixture to the remaining hot mixture and bring to a boil over medium heat, stirring constantly. Boil for one minute or until pudding thickens. Stir in the butter, vanilla extract and 1/2 Cup shredded coconut. Pour into prepared pie crust and chill. Cool completely before topping with Whipped topping.