01 - Line a baking sheet with parchment paper and set aside.
02 - In a medium saucepan over medium heat, combine the granulated sugar, unsalted butter, whole milk, unsweetened cocoa powder, and salt. Stir constantly until the mixture comes to a full rolling boil.
03 - Allow the mixture to boil for exactly 1 minute, stirring steadily. Remove the saucepan from heat immediately to prevent overcooking.
04 - Stir in the creamy peanut butter and vanilla extract until the mixture is smooth and fully blended.
05 - Gently fold in the old-fashioned rolled oats until every oat is evenly coated with the chocolate mixture.
06 - Drop spoonfuls of the mixture onto the prepared baking sheet, shaping into rounds as desired.
07 - Let the cookies cool at room temperature for about 20 minutes, or until fully set and firm.