In heavy saucepan, over low heat, melt semisweet chocolate with 1 cup sweetened condensed milk. Remove from heat; stir in vanilla. Spread half the mixture into wax paper line 8 or 9 inch square pan. Chill 10 minutes or until firm. Hold remaining chocolate mixture at room temperature. In heavy saucepan, over low heat, melt white chocolate with remaining sweetened condensed milk. Remove from heat; stir in peppermint extract and fool coloring. Spread on chilled chocolate layer. Chill 10 minutes longer or until firm. Spread reserved melted chocolate mixture on mint layer. Chill 2 hours or until firm. Turn onto cutting board. Peel off paper and cut into squares. Storre loosely covered at room temperature. Makes about 1-3/4 lbs.