Line 8 inch pan with wax paper. In a small bowl, microwave peanut butter chips and 2/3 cup of condensed milk. (high 1-1 1/2 minutes) Stir in vanilla until smooth. Repeat with chocolate chips. Spread peanut butter mix in pan. Spread chocolate mix on top. Cover and chill until firm. Cut into 1 inch pieces. Store in refrigerator.