1In food processor, place cookie mix. Cover; process 10 seconds or until chocolate chunks are finely chopped. Add oil and egg. Cover; process with on-and-off pulses until dough forms. Refrigerate 1 hour.
2Heat oven to 350°F. On lightly floured surface, roll dough to 1/4-inch thickness. Cut with 3-inch clover-shaped cookie cutter. On ungreased cookie sheets, place cutouts 2 inches apart. Insert 1 craft stick halfway into center of each cookie.
3Bake 8 to 10 minutes or until set. Cool 5 minutes; remove from cookie sheets to cooling racks. Cool completely.
4Divide frosting between 2 small bowls; tint 1 bowl with kelly green food color and 1 bowl with lime green food color. Frost half of the cookies with each color. Decorate with sanding sugar. Spoon remaining frosting into separate resealable food-storage plastic bags; cut off tiny corner of bags. Squeeze bag to pipe shamrock outlines on cookies. Let stand until set.