01 - In a large mixing bowl, beat together the creamy peanut butter, softened unsalted butter, vanilla extract, and fine sea salt using a hand mixer or stand mixer until the mixture is smooth and creamy.
02 - Gradually add the powdered sugar to the peanut butter mixture, mixing continuously until a thick, pliable dough forms that holds its shape when rolled.
03 - Scoop out heaping teaspoonfuls of the dough and roll them between your palms into smooth 1-inch balls. Arrange them on a parchment-lined baking sheet, leaving slight space between each.
04 - Place the baking sheet in the refrigerator and chill the peanut butter balls for at least 30 minutes, or until they are firm enough to handle without losing their shape during dipping.
05 - In a microwave-safe bowl, combine the chocolate chips with coconut oil or vegetable shortening if using. Microwave in 30-second increments, stirring thoroughly between each interval, until the chocolate is completely melted and smooth.
06 - Insert a toothpick into each chilled peanut butter ball and dip it into the melted chocolate, leaving the top quarter uncovered to create the signature buckeye appearance. Gently tap off any excess chocolate.
07 - Return each dipped ball to the parchment-lined baking sheet. Carefully remove the toothpick and use your finger to smooth over the small hole left behind if desired.
08 - Place the baking sheet back in the refrigerator and chill for about 20 minutes, or until the chocolate coating is fully set and firm to the touch.
09 - Serve the buckeye cookies chilled or allow them to sit at room temperature for 10 to 15 minutes for a softer texture. Store any leftovers in an airtight container in the refrigerator.