Start with lining a baking tray with parchment paper. If needed, spray the lining with cooking spray.

Heat butter, milk, and sugar on medium heat in a medium saucepan.

Stir the butter mixture until sugar is melted.

Remove the pan from the heat and whisk the mixture vigorously for 30 seconds to combine well.

Add peanut butter and vanilla to the same warm pan. Whisk until creamy and combined.

Now stir the oats into the peanut butter mixture.

With the help of an ice cream scooper or a tablespoon, scoop out the cookie mixture onto the lined baking and flatten them out.

Now cool the cookies for 30 minutes in refrigerate.

Serve them cool and enjoy.