Line two baking sheets with parchment paper or set out approximately 29 cupcake liners.
In a 2.5 to 3 quart medium saucepan combine butter, sugar, cocoa, and milk.
Remove from heat, immediately add in vanilla, peanut butter and quick oats.
Stir mixture until well combined then, using a medium (2 Tbsp) cookie scoop or two spoons drop mixture onto lined baking sheets or into cupcake liners.
Allow to rest at room temperature until set, about 20 - 30 minutes (to speed up setting refrigerate).
Store cookies in an airtight container at room temperature.