Spray a half-sized sheet pan (18"x13") with cooking spray and set aside.

In a very large bowl, add the oats and the peanut butter. No need to stir. Set aside.

In a large sauce pan over medium-high heat, combine the butter, cocoa powder, sugar, buttermilk and salt. Bring to a boil, stirring often. Boil for 1 and a half minutes, stirring constantly.

Remove the butter and chocolate mixture from the heat and pour over the oats and peanut butter. Stir until completely combined.

Spread the no bakes evenly into the prepared sheet pan. Allow to cool completely. Slice and serve. Wrap the bars individually in plastic wrap and keep in an air-tight container for several days.