Beat egg and evaporated milk in medium saucepan with wire whisk until well blended. Stir in granulated sugar. Add 1 cup of the Blue Bonnet. Bring to a boil over medium-low heat, stirring constantly. Remove from heat. Let stand 15 minutes, or until cooled. Add graham cracker crumbs, coconut and walnuts; mix well.
Beat confectioners' sugar, remaining 1/2 cup Blue Bonnet, the milk and vanilla with electric mixer on high speed until well blended. Spread over dessert; cover. Refrigerate overnight. Cut into 36 bars to serve.
Place half of the box of graham crackers in single layer in 13x9-inch pan, breaking crackers as needed to fit in pan. Pour Blue Bonnet mixture over crackers; spread to evenly cover crackers. Top with remaining graham crackers; press lightly into filling. Set aside.