Line your counter or baking sheet with parchment paper.
In a medium saucepan, bring the sugar, milk, butter and cocoa to a boil over medium heat, stirring occasionally.
Boil for 1 minute. Remove from the heat. Add the oats, peanut butter, vanilla and salt, and stir to combine.
Move really fast here so that cookies do harden too fast! If you went over the 1 minute boil mark, you might find that the cookies get dry really fast.
Drop teaspoonfuls of the mixture onto the prepared baking sheet or counter, and let sit at room temperature until cooled and hardened, about 30 minutes.
Store in an airtight container for up to 3 days. Easy to freeze for up to 2 weeks.