In a large mixing bowl, blend the peanut butter, softened butter, and vanilla extract until well combined.
Gradually add the powdered sugar, beating until the mixture holds together and can be shaped into balls.
Shape the peanut butter mixture into 1-inch balls and place on a baking sheet lined with wax paper. Refrigerate until firm, about 20 minutes.
In a microwave-safe bowl, combine chocolate chips and vegetable oil. Microwave on medium power in 30-second intervals, stirring in between, until chocolate is melted and smooth.
Using a toothpick, dip each peanut butter ball into the melted chocolate, leaving a small portion uncovered at the top to resemble a buckeye. Return the balls to the baking sheet.
Refrigerate the buckeye balls until the chocolate is set, about 15 minutes. Serve and enjoy!
Notes
Store buckeye balls in an airtight container in the refrigerator for up to 1 week. These can also be frozen for longer storage.