In your stand mixer, cream together the butter, vanilla, and peanut butter.
Slowly add the powdered sugar, mixing together. The mix will get very thick.
Scrape the sides of the mixer bowl and keep mixing until well incorporated.
Using a spoon, scoop out roughly tablespoon-sized clumps and roll into balls, placing on a cookie sheet.
Put the peanut butter balls into the freezer to chill for 30 minutes.
Put the chocolate and shortening in a microwave-safe bowl and nuke for 30 seconds. Stir, nuke for 20 seconds, and stir again. You're looking for smooth, well-incorporated chocolate.
Let the chocolate cool for about two minutes, so it's not scalding.
Remove the peanut butter balls from the freezer. Using a toothpick or skewer, dip the balls into the chocolate. Make sure they're almost, but not completely, covered in chocolate. You want that eye shape, after all.
Put the chocolate-covered buckeyes back on the cookie sheet after dipping, and dip the next. If the peanut butter balls are starting to crumble, return them to the freezer for another 10-15 minutes.
Once all of the buckeyes are coated, put them in the freezer or fridge to set, and they'll be ready to go.