01 -
Line a small baking sheet with parchment paper.
02 -
Add the butter, milk, cocoa powder, and sugar to a saucepan over medium heat.
03 -
Whisk to combine and heat the mixture until the sugar has dissolved.
04 -
Remove the saucepan from the heat, and stir in the vanilla, peanut butter, and oats until well combined.
05 -
Drop spoonfuls of the mixture on the parchment-lined baking sheet, and chill until the cookies have hardened.