In a saucepan, put the butter, granulated sugar, brown sugar, milk, and unsweetened cocoa powder over medium heat. Then, bring to a boil, stirring occasionally. Once the mixture is at a full boil, boil for one minute.
After boiling the mixture, mix in the peanut butter, vanilla, and salt. Once the mixture is well combined, add the oats and stir to coat.
Scoop out the cookie mixture and plop it onto the prepared baking sheet.
Allow the cookies to sit at room temp or in the fridge for 20-30 minutes or until they are fully set!