In a large bowl mix together the peanut butter, powdered sugar, melted butter, and vanilla.
You can use a stand mixer, hand mixer, or just a sturdy wooden spoon to mix it, it's up to you. Just be sure it's well combined to form a smooth thick dough.
Roll the peanut butter mixture into 1 inch balls using your hands (this will be about a tablespoon of dough). Place the prepared balls on a parchment paper lined baking sheet.
Melt your melting chocolate according to package directions (I generally use the double-boiler method on the stove after scorching a few too many batches of chocolate in the microwave).
Set the ball of peanut butter dough on a fork and lower it into the warm melted chocolate, taking care to not dip it fully, you should have a spot on the top that is about the size of a dime showing of the peanut butter, this is what makes it look like a buckeye.
Remove from the chocolate and gently tap the fork on the edge of your bowl to remove extra chocolate and then place the buckeye on a piece of parchment or waxed paper to set.
Repeat with remaining peanut butter balls and allow the chocolate to set before serving.
Store leftovers at room temperature.
Notes
You can find melting chocolate sold in big chunks during the holidays or you can look for melting chocolate near the chocolate chips.
Ghirardelli makes a good melting chocolate that comes in bags of both dark and milk chocolate. That's my preferred chocolate for this recipe. You can find it year round near the chocolate chips.
I don't recommend chocolate or brown almond bark for this recipe, it's a little waxy.
To prevent lumps, sift or whisk the powdered sugar before auditing it to the peanut butter mixture.
For evenly sized portions, use a cookie dough scoop when rolling the peanut butter mixture into balls.