Heat oven to 375 degrees F. In large bowl, stir cookie mix, oil, water and egg until soft dough forms.

Shape dough into 1-inch balls. On ungreased cookie sheets, place balls 2 inches apart.

Bake 8 to 9 minutes or until edges are light golden brown. Cool 2 minutes; remove from cookie sheets to cooling racks. Cool completely, about 15 minutes.

In small microwaveable bowl, microwave chocolate chips, butter and peanut butter uncovered on High 1 minute to 1 minute 30 seconds; stir until smooth. Stir in vanilla.

Place 1 1/2 cups powdered sugar in 1-gallon resealable food-storage plastic bag; set aside. Place 12 cooled cookies in large bowl. Pour 1/3 of chocolate mixture over cookies in bowl. Using rubber spatula, toss cookies gently to coat. Place cookies in bag with powdered sugar; seal bag. Gently turn bag to coat cookies. Remove cookies from bag to cooling rack to set. Repeat with 12 more cookies and 1/2 of remaining chocolate mixture; repeat again until all cookies are coated, adding additional powdered sugar to bag as needed.