Layered Chocolate Bars

1½ cups finely crushed thin pretzels
1½ sticks butter or margarine, melted
1 can (14 oz) sweetened condensed milk (not evaporated milk)
4 bars (4 oz) unsweetened baking chocolate, broken into pieces
2 cups minature marshmallows
1 cup sweetened coconut flakes
1 cup coarsely chopped pecans
4 bars (4 oz) semi-sweet baking chocolate, broken into pieces
1 tablespoon shortening

Heat oven to 350º. Combine pretzels and melted butter in small bowl; press evenly into bottom of 13x9 inch ungreased baking pan. Place sweetened condensed milk and unsweetened chocolate in small microwave-safe bowl. Microwave at high 1 to 1½ minutes or until mixture is melted and smooth when stirred. Pour over pretzel layer in pan. Top with marshmallows, coconut and pecans; press firmly down onto chocolate layer. Bake 25 to 30 minutes or until lightly browned; cool completely in pan on wire rack. Melt semi-sweet chocolate and shortening in small microwave-safe bowl on high for one minute or until melted when stirred; drizzle over entire top. Refrigerate 15 minutes or until set. Cut into bars.