Peanut Butter Cookies

1. Preheat oven to 350º F.
2. In a stand mixer fitted with a paddle attachment, blend together the butter, sugars, and peanut butter on medium speed until combined. Scrape down the sides of the bowl.
3. Add in the egg and mix until combined.
4. With the mixer on low, add in the flour, baking soda, and salt and mix just until combined, scraping down the sides of the bowl as needed.
5. Place the bowl of dough in the fridge to chill for at least 10 minutes.
6. Using a 2 tablespoon scoop, form cookies into balls. Roll the tops of each in sugar. Place each cookie on a parchment lined cookie sheet a few inches apart.
7. Bake the cookies for about 12-14 minutes. Let the cookies cool for about 10 minutes on the baking sheet before carefully moving them to a cooling rack.

Marshmallow Fluff

1. Once the cookies are cooled, stir together the egg whites, sugar, and cream of tartar in a double boiler. Continue to stir constantly until mixture reaches 160º F on a candy thermometer.
2. Transfer to a mixing bowl, add in the vanilla, and mix with the whisk attachment on medium-high speed for 3-4 minutes followed by high speed for another 5-6 minutes until stiff peaks have formed.
3. Immediately transfer to a pastry bag with an Ateco 807 or similar piping tip. If you don't have that type of big round piping tip, cut the tip of the bag until you have a hole about the size of a penny.

Assembly

1. Turn half of the cookies upside down. Starting on the outer rim of the bottom of the cookie, pipe a swirl, moving further into the center.
2. Top with another cookie so that the tops of the cookies are facing outward. Repeat this process with the rest of the cookies. Enjoy!