01 - In a large mixing bowl, beat together the peanut butter, softened butter, vanilla extract, and salt until smooth and creamy.
02 - Gradually add powdered sugar, mixing until a thick, pliable dough forms.
03 - Scoop out heaping teaspoonfuls of the peanut butter mixture and roll into 1-inch balls. Place on a parchment-lined baking sheet.
04 - Chill the peanut butter balls in the refrigerator for at least 30 minutes, or until firm.
05 - In a microwave-safe bowl, melt chocolate chips with coconut oil (if using) in 30-second increments, stirring until smooth.
06 - Using a toothpick, dip each peanut butter ball into the melted chocolate, leaving the top portion uncovered to resemble a buckeye.
07 - Return the coated balls to the baking sheet and remove the toothpick, smoothing over the hole if desired.
08 - Refrigerate the cookies until the chocolate is set, about 20 minutes.
09 - Serve chilled or at room temperature. Store leftover cookies in an airtight container in the refrigerator.