MELT chocolate chips with 1 cup sweetened condensed milk in heavy saucepan over low heat; add vanilla. Spread half the mixture into prepared pan; chill 10 minutes or until firm. Hold remaining chocolate mixture at room temperature.
MELT white confectioners' coating with remaining sweetened condensed milk in heavy saucepan over low heat (mixture will be thick). Add peppermint extract and food coloring, if desired. Spread on chilled chocolate layer; chill an additional 10 minutes or until firm.
SPREAD reserved chocolate mixture on mint layer. Chill 2 hours or until firm. Remove from pan by lifting edges of wax paper; peel off paper. Cut into squares.
*Confectioners' coating can be purchased in candy specialty store