Adapted from Rachel Schultz and Charlotte Oates
Peanut butter & chocolate paired in a soft chewy cup
Preheat oven to 350°F. Line 2 medium sized muffin tins with shallow paper liners or lightly grease tins.
In a stand mixer (or using a hand-held mixer), combine butter, peanut butter, sugar, and brown sugar. Add egg and vanilla, continuing to mix.
In a separate bowl whisk together baking soda, salt, and flour. Slowly add the dry ingredients to the peanut butter mixture. Continue to mix until well combined and the dough is formed.
Scoop 1 1/2 tablespoons of the dough into each muffin cup. With your fingertips, gently press the dough around the bottom of the cup to form a base. Using the base of a rounded measuring spoon, press a small round indentation into the dough in each muffin cup.
Bake for 10 to 12 minutes. Remove the pans from the oven and place them on a wire rack to cool. If the cookies have puffed up in the center, gently recreate the indentation in the center.
When completely cooled, top each cup with piped (or spread) Nutella Buttercream.
Cut the butter into cubes and beat with an electric mixer until creamy.
Very slowly add the confectioners' sugar with the mixer set on slow speed. Once the sugar has been fully incorporated, increase the mixer speed to medium and add the Nutella along with a pinch of salt.
Check the consistency of the buttercream. If it is too thick to spread or pipe, add 1/2 teaspoon milk. Mix well and repeat until the consistency is right.
This recipe makes enough for to fill 24 peanut butter cups, to make 12 buttercream cupcake roses or for a thin covering over an 8-inch cake with a layer in the middle.