Peanut Butter-Oatmeal Cookie Sandwiches with Nutella Buttercream

Preheat the oven to 350ºF. Combine the flour, baking soda, baking powder, and salt in a large bowl; set aside.

In the bowl of a stand mixer, cream the butter, peanut butter, white sugar, brown sugar, and vanilla until creamy and well-blended. Add the egg and mix until incorporated. Scrape down the sides of the bowl as needed.

Add the dry ingredients to the creamed mixture in a couple of batches and mix until fully incorporated. Stir in the oatmeal and drop by rounded teaspoonfuls onto a baking sheet lined with parchment paper. Gently flatten each cookie with a spatula to form 1/4 inch thick cookies and bake 9-10 minutes, or until cookies are a lightly browned. Cool on a wire rack and cool completely before filling.

For the buttercream filling, mix the butter and Nutella in the bowl of a stand mixer until combined. Add the powdered sugar, a little at a time and mix completely after each addition. After 1 cup of powdered sugar has been incorporated, add 1 tablespoon milk and mix well. At this point, add more powdered sugar if the consistency is too thin and more milk if the buttercream is too thick. I chose to pipe the buttercream onto the cookies. First, because I’m obsessed with piping; second, because I love the Wilton 1M tip; third, because it seemed to me like the least-messy way to actually assemble the cookies. I’m a mess in the kitchen!