LINE baking sheets with wax paper.
BEAT peanut butter and butter in large mixer bowl until creamy. Beat in powdered sugar until mixture holds together and is moistened. Shape into 1-inch balls; place on prepared baking sheets. Freeze for 1 hour.
MELT morsels and shortening in medium, uncovered, microwave-safe bowl on HIGH (100%) power for 1 minute; STIR. Morsels may retain some of their shape. If necessary, microwave at additional 10- to 15-second intervals, stirring just until melted.
DIP peanut butter centers into melted chocolate using a toothpick, leaving a small portion of the center uncovered. Shake off excess chocolate and scrape bottom of candy on side of bowl. Return to baking sheets; refrigerate until chocolate is set. Store in covered container in refrigerator.