Line 8x8 inch pan with wax paper, grease paper. Combine chocolate chips, butter, and sweetened condensed milk in a microwave safe bowl. Heat for 1 minute on high. Stir until melted and well blended. (If necessary, reheat in 10 second intervals followed by stirring.)
Add vanilla and crushed candy bars, mix well.
Pour mixture into pan and refrigerate until firm, at least 2 hours. Remove from pan and wax paper by turning over onto cutting surface and peeling off paper. Cut into small squares.