Combine the butter, sugar, milk, and cocoa powder together in a medium saucepan (about 3 quart) over medium heat.
Whisk constantly until the butter melts.
Whisking occasionally, bring to a boil.
Once boiling, stop whisking and allow to boil for 1 minute.
Remove from heat, then immediately stir in the peanut butter and vanilla extract until completely combined.
Stir in the oats and salt.
Allow mixture to sit for 5 minutes.
During the 5 minutes, line two baking sheets with parchment paper or silicone baking mats.
Using a 1-Tablespoon cookie scoop (or simply a spoon), drop a Tablespoon of dough onto the lined baking sheets.
If desired, slightly flatten down with the back of a spoon.
Refrigerate the cookies for 30-60 minutes so they set.
Remove from the refrigerator and enjoy!
