Scald milk in top of double boiler. Beat the egg yolks and add sugar. Add this mixture gradually to scalded milk. Stir constantly, allowing to cook for 1 minute. Then add cracker crumbs and coconut. Stir until crumbs are soft and mixture is thick. Remove from heat and add vanilla. Pour into a buttered baking dish. Spread with meringue made by beating 3 tablespoons sugar into stiffly beaten egg whites. Bake at 350ºF. until meringue is a golden brown.