Heat oven to 375°F (190 C). Combine all cookie ingredients except flour and 1 cup mini chocolate chips in large mixer bowl. Beat at medium speed until creamy (1 to 2 minutes).
Reduce speed to low. Add flour; beat until mixture forms a dough (1 to 2 minutes). Stir in 1 cup mini chocolate chips by hand.
Roll dough into 1-inch balls. Place 2 inches apart onto ungreased cookie sheet. Flatten to 1 1/2-inch circle with bottom of glass dipped in flour (See Tip Below). Bake for 5 to 7 minutes or until set. (DO NOT OVER BAKE.) Let stand 2 minutes; remove from cookie sheet. Cool completely on wire rack.
Combine all frosting ingredients in small mixer bowl. Beat at low speed, adding milk, 1 teaspoonful at a time, if necessary until frosting is smooth. Frost cooled cookies. Place on waxed paper.
Place 1/2 cup mini chocolate chips and shortening in small microwave-safe bowl. Microwave on HIGH, stirring every 30 seconds, until smooth (60 to 90 seconds). Drizzle thin lines of chocolate over frosting with teaspoon. Let stand until chocolate is set (at least 30 minutes).
If desired, place melted chocolate in small resealable plastic food bag. Cut tiny tip off one corner of bag to drizzle chocolate.
Makes: 3 1/2 dozen cookies
To measure flour, lightly spoon flour into metal or plastic dry measuring cup. Level off excess with table knife. (Do not dip cup into flour or pack flour into cup.)
Tips from Sadie, a Guest to Diana's Desserts:
If the cookie dough is a bit sticky, chill for a few minutes in the refrigerator before rolling out.
Add a teaspoon of cocoa to the flour when flatening cookies with bottom of glass.
Date: January 17, 2006