Preheat oven to 350 degrees F. Line a sheet pan with parchment paper and set aside

In the bowl of a standmixer, fitted with a paddle attachment, add the unsalted butter, peanut butter, and sugar mix until fluffy and light, about 5 minutes. Scrape down the sides of the bowl with a nonstick spatula

In a small separate bowl, add the egg whites. Then using a fork, beat the egg whites with a fork until foamy and thin, then add to the butter and sugar. Mix on low until combined

Add in the flour, baking soda and salt. Gently mix to form a soft dough. You can use immediately. Alternatively, you can wrap the dough in cling wrap and refrigerate for one week (just let the dough come to room temp before you roll

Prepare the work surface by sprinkling flour on a clean space. This will ensure that the dough does not stick to the counter as you roll. Roll the dough out to about ⅛ of an inch thick. The thinner the cookie, the crispier, the thicker- the softer and chewier! Use your cookie cutter to cut (and stamp if you have a peanut cutter) the dough.

Transfer cut cookie dough pieces onto the prepared baking sheet. Making sure that you place them at least 1.5 inches apart. Bake for 11-15 minutes. Cookies will be firm and even in color.

In a large bowl, with a hand-mixer or in the bowl of a stand mixer fitted with a paddle attachment add the peanut butter, butter, honey, and salt. Mix until thoroughly combined (about 2 minutes in the stand mixer and 4 minutes with a hand-mixer).

Scrape down the sides of the bowl with a nonstick spatula an add in the confectioner's sugar. Mix until thick dough forms. Remove filling from bowl (you can use your hands during this part, it gets a little messy) and place on a piece of parchment paper. Place another piece of parchment on top and use a rolling pin to roll it out flat. It will be sticky. Roll it to ⅓ inch depending on how much filling you want.

Using the same cutter you used for the cookies, cut the filling into a peanut shape. Carefully move the filling from the parchment to ½ of the prepared and COOLED cookies. Use the other ½ of the cookies to sandwich on top of the cookies with the filling.