Combine peanut butter, butter, vanilla and salt in large bowl. Beat with an electric mixer on LOW until blended. Add 2 cups powdered sugar, beating until blended. Beat in additional powdered sugar until mixture, when shaped into a ball, will stay on a toothpick. Shape into 1-inch balls. Refrigerate.
Place chocolate chips and shortening in microwave-safe bowl. Microwave on MEDIUM for 30 seconds. Stir. Repeat until mixture is smooth. Reheat as needed while coating peanut butter balls.
Insert toothpick in peanut butter ball. Dip 3/4 of ball into chocolate, leaving top uncovered to resemble a buckeye. Remove excess. Place on wax paper-lined tray. Remove toothpick. Smooth over holes. Refrigerate until firm.