MELT 2 squares chocolate, 2/3 cup sweetened condensed milk and butter in large saucepan over low heat; remove from heat. Stir in crumbs, nuts and 1 teaspoon vanilla. Press firmly into bottom of 12 x 7-inch baking dish; chill 15 minutes.

BEAT cream cheese in small bowl until fluffy. Beat in sugar until smooth. Stir in peppermint extract and food coloring. Spread over chocolate layer; chill an additional 45 minutes or until mint layer is set.

MELT remaining 2 squares chocolate with remaining sweetened condensed milk in small saucepan over low heat. Remove from heat; stir in remaining 1/2 teaspoon vanilla. Spread over mint layer. Chill 2 hours or until firm. Cut into bars.