Line a baking sheet with wax paper or parchment, or just lay it on your counter.
Melt the butter in a medium/large sauce pan. Once melted, add the sugar, milk, peanut butter, vanilla and cocoa mixing thoroughly to combine. Bring to a boil over medium/high heat, stirring occasionally, then let boil for 3 minutes stirring constantly. Mix in oats and remove from the heat. Drop tablespoonfuls of the mixture onto the prepared baking sheet, and let sit at room temperature until cooled and hardened, about 30 minutes. Refrigerate in an airtight container.
I like to add a couple of teaspoons of flax seed and some coconut flakes too mine as well.