Start by combining peanut butter, butter, vanilla and salt in a large mixing bowl until smooth and creamy.
Mix in 3 cups sifted powdered sugar until well blended. Shape a spoonful of peanut butter into a 1-inch ball. Your peanut butter batter should be easy to work with and shouldn't stick to your hands.
Once your peanut butter balls are rolled, place them on a cookie sheet lined with parchment paper. Chill for 30 minutes in the freezer or 45 minutes in the refrigerator.
Pour chocolate chips, espresso powder and add the shortening to a work bowl on top of a double boiler. I use a standard cook pot and place a glass or stainless bowl so that it sits on top.
Add 1 cup of water in the bottom pan of the double boiler and simmer on medium. As the top bowl warms from the steam of the hot water below it, stir the melting chocolate until it is smooth. Remove the melted chocolate from the stove.
Grab your chilled peanut butter balls and insert a toothpick into the top of each ball. Gently dip 3/4 of ball into the melted chocolate, leaving the top uncovered. Allow excess chocolate to drip from the buckeye then place the buckeye back onto your parchment paper lined baking sheet.
Return your buckeyes to chill again for another 15 minutes then remove the toothpick and smooth over the holes with your fingertip.