In a medium saucepan over medium heat, combine butter, sugar, milk, and cocoa powder.
Stir frequently until the mixture comes to a full boil.
Once boiling, let it cook for 1 minute while stirring.
Remove from heat and quickly stir in the peanut butter, vanilla, and salt until smooth.
Fold in the oats until everything is evenly combined.
Drop spoonfuls of the mixture onto wax paper and let cool until firm, about 20-30 minutes.