Layered Mint Chocolate Fudge

Preparation : *Or, use 6 ounces white confectioners' coating. In heavy saucepan, over low heat, melt chips with 1 cup sweetened condensed milk; add vanilla. Spread half the mixture into wax paper-lined 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 baking pieces with remaining sweetened condensed milk ( mixture will be thick). Add peppermint extract and food coloring if desired. Spread on chilled chocolate layer; chill 10 minutes longer or until firm. Spread reserved chocolate mixture on mint layer. Chill 2 hours or until fir