07Melt 1 ½ cups chocolate chips and condensed sweetened milk over medium heat.08Stir in vanilla.09Spread mixture over hot crust.10Stir walnuts and remaining ½ cup chocolate chips into reserved crumb mixture.11Sprinkle crumb mixture over chocolate filling.12Bake for 25-30 minutes or until center is set.13Cool and cut into bars.14Makes 24-36 bars depending on desired size.15Store at room temperature.