Make the peanut butter filling. Stir together the peanut butter and powdered sugar until smooth. Use a small cookie scoop to scoop out the filling onto a plate or cookie sheet lined with wax paper. You should be able to make about 20-22 balls. Place in freezer for about 30 minutes.
While the peanut butter balls are freezing, you can make the cookie dough. Cream the butter and sugars together with an electric mixer for about 2-3 minutes. Add the egg and vanilla and continue to mix for 1-2 more minutes. Add the flour, cocoa powder, baking soda and salt and continue to mix until smooth.
Scoop out a heaping tablespoonful of cookie dough (I used a medium cookie scoop or you can just overfill a small one) and flatten it out between your hands like a pancake. Place a frozen peanut butter ball on top and then fold up the edges of the cookie until the peanut butter ball is completely covered. If it doesn't look like a ball at this point, roll it between your palms to form a ball. (Unless you have a couple of people making these, you'll want to keep at least half of the peanut butter balls in the freezer when you first begin, and then work quickly so that the peanut butter doesn't start thawing as you are assembling the cookies- the process gets a lot messier once it starts to thaw out!)
Place some sugar in a shallow bowl and gently roll the cookie ball in the sugar until coated on all sides. The sugar will help prevent the balls from sticking to the cookie sheets, makes the cookies prettier, and adds a nice little texture to the cookies as well!
Place the cookie balls at least 2" apart on a prepared cookie sheet. You can use well-greased cookie sheets or you can use cookie sheets lined with parchment paper or silicone baking mats. I prefer the silicone baking mats because nothing sticks to them!
Bake for about 10-12 minutes. I usually stick to the lower end of baking times on cookies because I like them really soft, but if you like them a little bit firmer and well-done, you can bake them a minute or two longer.
Let cool on the baking sheets for about 10-15 minutes before transferring to a wire rack. These cookies are delicious warm, but the peanut butter filling stays gooey even when they are completely cooled and up to a few days later as well!
Buckeye Cookies https://familycookierecipes.com/buckeye-cookies/