Preheat oven to 350 degrees. Spray a rimmed 18 by 13-inch cookie sheet with non-stick cooking spray.

In a mixing bowl whisk together flour, oats, baking soda and salt. Set aside.

In the bowl of an electric stand mixer fitted with the paddle attachment, blend together butter, brown sugar and granulated sugar until creamy.

Mix in eggs one at a time. Then blend in 1 cup peanut butter and the vanilla.

Add in flour mixture and mix just until combined.

Drop cookie dough onto prepared baking sheet. Spray hands with non-stick cooking spray and spread dough into an even layer.

Bake in preheated oven 13-15 minutes until golden.

Remove from oven and cool 5 minutes, then dollop remaining 1 cup peanut butter by spoonfuls over top. Let sit 1 minute then spread peanut butter into an even layer to cover top.

Melt butter in a medium saucepan. Stir in cocoa, milk and salt and bring mixture just to a boil over medium heat.

Remove from heat and whisk in vanilla, then stir in powdered sugar and mix until well combined.

Immediately pour over bars and spread into an even layer. Allow frosting to set then cut into squares. Store in an airtight container.