Line an 8-inch square baking pan with aluminum foil or wax paper, extending foil over two sides of pan. Butter foil.
Combine chocolate and sweetened condensed milk in a large microwave-safe bowl. Microwave on high for 2 minutes or until chocolate softens, stirring after each minute. Stir mixture until chocolate melts. Do not over cook!
Stir in pecans, coconut and vanilla. Spread mixture into prepared pan.
Cover and chill 2 hours or until firm. Cut into 1-inch squares. Store in an airtight container in a cool place. Makes about 4 dozen pieces.