Line two baking sheets with parchment paper or wax paper and set aside.
Bring sugar, butter, milk, and cocoa powder to a rolling boil in a medium-size saucepan over medium heat, stirring often. Once it has reached a full boil allow it to boil for 60 seconds, stirring frequently.
Remove the sugar mixture from heat and immediately stir in the peanut butter, vanilla extract, and oats until well combined.
Drop spoonfuls onto prepared baking sheets and allow to set at room temperature until cooled and hardened, about 30 minutes.
