In a large bowl, mix together peanut butter, softened butter, and vanilla until smooth and well combined.
Gradually add powdered sugar, mixing until a thick dough forms. You might need to use your hands for the last bit – it should be firm enough to roll into balls.
Roll the mixture into 1-inch balls and place on a parchment-lined baking sheet. Insert a toothpick into each ball and freeze for 30 minutes.
Melt chocolate chips and shortening together in a microwave-safe bowl in 30-second intervals, stirring between each, until smooth.
Holding each peanut butter ball by the toothpick, dip into the melted chocolate, leaving a small circle of peanut butter visible at the top to create the "buckeye" look.
Place back on parchment paper and smooth over the toothpick hole with your finger. Refrigerate until chocolate is set, about 30 minutes. Store in the refrigerator in an airtight container.