Combine peanut butter, sugar and butter in small bowl until well blended. If mixture is very soft, mix in an additional tablespoon of sugar. Shape peanut butter mixture into 30 1/2- to 3/4-inch balls flattening slightly.
Melt morsels and shortening in medium, uncovered, microwave-safe bowl on MEDIUM-HIGH (70%) 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. Spoon 1 measuring teaspoon of melted morsels into each cup. Place peanut butter filling onto top of melted morsels. Top each with a measuring half teaspoon of melted morsels. Sprinkle with a few grains of sea salt. Refrigerate for 20 minutes or until firm. Store in covered container in refrigerator.
TIP: To keep melted chocolate warm, place bowl on top of smaller bowl filled with very warm water. Do not allow water to touch bottom of bowl or allow water to get into chocolate.