Preheat your oven to 350 degrees and thoroughly grease a mini muffin tin. Set aside.
Make your brownie batter according to box instructions, then divide the batter evenly among the 24 mini muffin tin cavities (they’ll be about ½ full).
Bake the brownies for 18-20 minutes, then let cool for 5 minutes.
Using the handle of a wooden spoon or cooking spatula, press down to make an indentation halfway deep in the center of each brownie bite. Set aside to cool fully.
In a medium mixing bowl combine creamy peanut butter, powdered sugar, softened butter, and vanilla extract. Mix until there is no residual powdered sugar, and the mixture is smooth.
Roll the peanut butter mixture into 24 equal sized balls (about ½ inch in size) then lightly press them into the brownie bite indentations.
Melt chocolate chips in the microwave in 30 second intervals or until smooth. Drizzle the melted chocolate over the buckeye bites, then let the chocolate set before removing the buckeye bites from the pan.