Beat butter at medium speed with an electric mixer about 2 minutes or until creamy. Gradually add powdered sugar, beating until smooth. Stir in espresso beans, Kahlúa, and salt. Cover and chill 1 hour or until firm. Shape mixture by teaspoonfuls into balls, and flatten slightly.
Melt chocolate morsels and shortening in a small saucepan over low heat, stirring until smooth. Spoon 1/2 teaspoon melted chocolate into 48 paper-lined miniature (1 3/4") muffin pans, turning pans to coat bottoms evenly. Place 1 Kahlúa ball in each cup; spoon remaining melted chocolate over Kahlúa balls, covering them completely. Cover and chill chocolate cups until firm. Store in an airtight container in refrigerator.