01 - Line two baking sheets with parchment paper or silicone baking mats and set aside.
02 - In a medium saucepan over medium heat, melt the butter. Add the granulated sugar and whole milk, stirring until the sugar dissolves and the mixture is well combined.
03 - Bring the mixture to a gentle boil, stirring constantly. Once it reaches a full boil, stop stirring and let it cook for exactly 1 minute to ensure proper setting.
04 - Remove the saucepan from heat. Immediately stir in the creamy peanut butter, pure vanilla extract, and a pinch of salt until the mixture is completely smooth and uniform.
05 - Quickly fold in the quick-cooking oats, stirring until every oat is evenly coated and well combined. Work promptly as the mixture will begin to thicken.
06 - Using a tablespoon or cookie scoop, drop rounded portions of the mixture onto the prepared baking sheets, spacing them about 1 inch apart.
07 - Allow the cookies to cool undisturbed at room temperature for 10 to 15 minutes until firm and fully set.
08 - Once the cookies have hardened completely, transfer them to an airtight container with layers separated by parchment paper. Store at room temperature for up to 1 week.