Lightly grease 9-inch square pan. In medium saucepan, combine 1/2 cup butter and 1/4 cup of the vanilla chips. Cook over low heat until melted, stirring constantly. Remove from heat.
Stir in wafer crumbs until well mixed. Press mixture evenly in greased pan.
In small saucepan, melt remaining 3/4 cup vanilla chips over low heat, stirring constantly.
In small bowl, combine 2 tablespoons butter, milk and vanilla; mix well. Gradually beat in melted chips and powdered sugar until smooth.
Spread jam over crumb mixture. Spread chip mixture over jam. Sprinkle with walnuts. Refrigerate 10 to 15 minutes or until set. Cut into bars. Serve bars at room temperature.