Preheat the oven to 350°F. Grease a jelly roll pan (12”x17”) and set aside.
In the bowl of a standing mixer, beat together the butter and 1 cup of the peanut butter until fluffy and well blended. Scrape down the sides of the bowl.
Add granulated sugar and brown sugar to the butter mixture and beat well (1-2 minutes).
Add in the eggs and vanilla extract and beat on medium-high for another 2-3 minutes, scraping down the sides and bottom of the bowl intermittently to ensure even mixing.
In a separate bowl, stir together the salt, baking soda, flour, and oats.
Add the flour mixture to the creamed ingredients and beat just until combined (do not overmix).
Use a spatula or greased hands to pat the cookie dough into the prepared sheet pan.
Bake for 16 minutes, until the center is set and the edges of the cookie are golden brown. Remove from the oven.
In a microwave-safe bowl, heat the remaining 1 cup of peanut butter for 30 seconds-1 minutes, until it is mostly melted and easily spreadable. Pour the melted peanut butter over the baked cookies and spread to the edges. Allow the cookies to cool completely - once room temperature, you can place the pan into the refrigerator to help the peanut butter set again and make it easier to frost.
To make the frosting, beat the butter with an electric mixer.
Add in the cocoa powder, powdered sugar, vanilla extract, and a pinch of salt. The mixture will be very dry.
Drizzle the heavy cream into the bowl with the mixer running and beat until light and fluffy.
Spread frosting over the cooled peanut butter cookie base.
Cut into bars and serve.
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Notes
Storage:Keep leftovers in an airtight container in the refrigerator or on the counter for up to 5 days (in an airtight container). Freeze for up to 1 month.Notes:Old fashioned rolled oats are a must. They are larger and thicker, so they have the best chew without making the bars dry. The base is super soft and chewy, sweet, and filled with peanut butter flavor. We love the melted peanut butter layer, but it is option. Microwaving the peanut butter is a quick way to make it easily spreadable, but you can also scoop it out onto the hot cookie base and spread it as it melts naturally. The chocolate frosting is a basic buttercream that compliments the bars well, but you can also use your favorite frosting recipe. Chilling the base makes frosting easier without damaging the peanut butter layer.