Combine peanut butter, softened butter, and vanilla in a large mixing bowl and mix with an electric mixer on medium speed until evenly combined.
Add the powdered sugar and beat until well combined.
Scoop approximately 2 tablespoons of the dough. Form balls by rolling them between your palms. Arrange the peanut butter balls on the prepared baking sheet.Pro Tip: Every brand of peanut butter contains different amounts of oil and sugar. Depending on the brand of peanut butter you use, you may have to adjust the recipe slightly. When you roll the peanut butter mixture into a ball, the batter should not stick to your hands and you should not have a problem rolling it into a smooth ball. If the batter is crumbly, add a small amount of additional peanut butter. If the batter is too sticky, add powdered sugar.
Cover and refrigerate the balls until firm, at least 20 minutes.
In a medium-sized microwave-safe bowl, combine the chocolate and oil. Microwave in 20-second intervals, stirring in between until the chocolate is almost completely melted.
Remove the bowl from the microwave and stir until the chocolate has completely melted. Set the bowl aside to cool to room temperature.Pro Tip: Alternatively, you can melt the chocolate by combining the oil and chocolate in a medium-sized glass bowl placed over a pan of simmering water on a stove. Stir until the chocolate has completely melted.
Insert a toothpick or skewer about ¾ the way into a peanut butter ball. Dip the peanut butter balls into the melted chocolate leaving a small amount of the top uncovered so that the candy resembles a buckeye.
Allow the excess chocolate to drip back into the bowl and then place the buckeye on the lined baking sheet. Repeat with the remaining peanut butter balls.
Remove the toothpick and refrigerate until firm. Use the tip of a knife over the tops to smooth out the holes.
Refrigerate in an airtight container. Buckeyes keep well for 2 weeks in the refrigerator and up to 3 months when stored in the freezer.
Notes
For Smooth Dough: Start by blending the peanut butter, butter, and vanilla together. Once that's well mixed, gradually incorporate the powdered sugar to avoid dry, crumbly dough.
Eliminate Toothpick Marks: To hide any toothpick holes, you can use a knife to gently smooth the area or lightly dampen your fingertips with water and rub over the holes for a flawless finish.
Use Leftover Melted Chocolate: If you find yourself with extra melted chocolate, spread it onto a fresh sheet of parchment paper to let it harden. Once solid, peel it off, break it into chunks, and save it for future recipes.
Butter Softening Tips: For optimally softened butter, leave it on your kitchen counter for about 30 minutes before you plan to use it.