Line 8 inch square pan with foil, leaving 1 inch overhang on the sides. Place semisweet chocolate on top of double boiler over simmering water. Stir until melted. Remove from heat.

Spread melted chocolate onto bottom of prepared pan. Let stand until firm.

Melt white chocolate in clean double boiler; stir in peppermint extract. Spread over set semi sweet chocolate layer. Shake pan to spread evenly. Let stand 45 minutes or until set.

Melt milk chocolate in same double boiler. Spread over white chocolate layer. Shake pan to spread evenly. Let stand 45 minutes or until set.

Cut mints into 16 2inch squares. Remove from pan by lifting mints and foil with foil handles. Cut each square diagonally into 2 triangles. Cut in half again to make 64 small triangles.

Store in airtight container in refrigerator.