Begin by prepping all of your ingredients and have them readily accessible. This includes lining 2 baking sheets with parchment paper or silicon cookie sheets. 

Next, in a large saucepan on medium high heat, melt your butter. Add in your cocoa powder, sugar and milk next and whisk together to incorporate. Let this cook and come to a rolling boil. Once it's boiling, let it boil for 2 full minutes. Set a time if needed. This will ensure that the mixture thickens and cook the oats. 

Once it's boiled for 2 minutes, take it off the heat immediately. Stir in your peanut butter and vanilla extract. Mix until smooth. Lastly, add in your oats and mix together until incorporated. 

Once your cookie mixture is all mixed, using a tablespoon or large cookie scoop, scoop out about 1-2 tbsp worth of mixture per cookie. Feel free to lightly flatted and shape them into round neat cookies using a fork. 

Let them harden and set for about 15 minutes, either in your room temperature kitchen OR if you want them to be set quicker, place them in your refrigerator.