Grab all of your ingredients and measure them all out before starting the recipe. This recipe moves quickly, so it's helpful to have everthing prepped and ready.
Line two baking sheets with parchment paper or set out a couple of large sheets of parchment paper on your countertop.
In a 2.5 to 3 quart medium saucepan combine sugar, cocoa, butter, and milk.
Set over medium heat, and cook stirring frequently until it reaches a full boil. Be patient, this can take up to about 10 minutes, but you don't want to turn the heat up because the bottom of the mixture will burn.
Once the mixture comes to a full boil (not just a simmer), set your timer for 1 minute 30 seconds. Conutine to cook and stir until timer goes off.
Remove from heat, then immediately stir in the peanut butter and vanilla extract until completely combined. Stir in the oats and salt. Mix well and using a 1-tablespoon cookie scoop or a spoon, drop a tablespoon of dough onto the parchment paper. Repeat with the rest of the dough. Let cool.
Allow cookies to rest at room temperature until set, about 20 - 30 minutes. Store cookies in an airtight container at room temperature.