Prepare a cookie tray by lining it with parchment paper or a silicone mat.
To a large pot over medium heat add the sugar, milk, butter, vanilla, and cocoa powder. Bring to a boil and then cook for one minute.
Add the peanut butter to the chocolate mixture and stir till melted.
Pour in the quick cooking oats and stir to combine. (You can pour the oats into the pot or pour the chocolate peanut butter mixture over the oats in a bowl.)
Drop spoonfuls of the oat mixture onto the prepared baking sheet. Allow the cookies to cool for 30 minutes in the fridge or flash freeze for 15 minutes. Serve immediately or store for later. (see note)
Store cookies in air tight container in the refrigerator for up to 1 week.