Mix 1/4 cup of the sugar with the corn-starch and salt. Gradually stir in the scalded milk. Add the butter.
Cook the mixture in a double boiler, stirring constantly, until thickened.
Beat the egg yolks, add a little of the thickened mixture, blend and stir into the remaining hot mixture. Cook, stirring, until thickened. Cool slightly.
Add the vanilla and 3/4 cup of the coconut. Turn into the baked pie shell.
Beat the egg whites until foamy. Gradually add the remaining sugar and beat until stiff but not dry. Spread over the filling, making sure that the meringue touches the crust at all points. Sprinkle with the remaining coconut and bake until light brown, or about 15 minutes. Cool before serving.