In a large bowl, cream together the peanut butter and butter until smooth.
Gradually add the powdered sugar and vanilla, mixing until well combined.
Roll the mixture into 1-inch balls and place on a parchment-lined baking sheet.
Chill in the freezer or refrigerator for at least 30 minutes.
Melt the chocolate chips and shortening in a double boiler or microwave, stirring until smooth.
Dip each ball into the melted chocolate, coating completely.
Return to the baking sheet and sprinkle with sea salt (if using).
Chill again until the chocolate is set.