Beat peanut butter and butter at medium speed with an electric mixer until blended. Gradually add powdered sugar, beating until blended.

Shape into 1-inch balls; chill 10 minutes or until firm.

Microwave chocolate and shortening in a 2-quart glass bowl at HIGH 1 1/2 minutes or until melted, stirring twice.

Dip each ball in chocolate mixture until partially coated; place on wax paper to harden. Store in an airtight container.