01 - In a large mixing bowl, beat together the peanut butter, softened butter, vanilla extract, and salt using a hand mixer or stand mixer until smooth and creamy.
02 - Gradually add the powdered sugar, mixing continuously until a thick, pliable dough forms that holds its shape when rolled.
03 - Scoop out heaping teaspoonfuls of the peanut butter mixture and roll into 1-inch balls. Arrange them on a parchment-lined baking sheet, spacing evenly.
04 - Place the baking sheet in the refrigerator and chill the peanut butter balls for at least 30 minutes, or until firm to the touch.
05 - In a microwave-safe bowl, combine the chocolate chips with coconut oil if using. Microwave in 30-second increments, stirring between each interval, until completely smooth and glossy.
06 - Using a toothpick inserted into the top of each chilled peanut butter ball, dip into the melted chocolate, leaving the top center uncovered to resemble a buckeye nut.
07 - Return each coated ball to the parchment-lined baking sheet. Remove the toothpick and gently smooth over any visible holes with your finger.
08 - Refrigerate the dipped cookies for about 20 minutes, or until the chocolate coating is fully set and firm.
09 - Serve chilled or allow to sit at room temperature for 10 to 15 minutes for a softer texture. Store any leftovers in an airtight container in the refrigerator.