Measure the flour accurately by leveling it off with a knife after spooning it into the measuring cup. Sift the flour into a bowl.

In the bowl of a stand mixer, combine the butter, peanut butter, sugar, baking soda, and salt. Start mixing on low speed until just blended, then increase the speed to medium and beat until the mixture is light and fluffy, which should take about 5 minutes.

Lightly beat the egg whites in a separate bowl until smooth and thin, then gradually add them to the butter mixture, ensuring they’re fully incorporated. Slowly mix in the sifted flour until a soft dough forms.

Knead the dough by hand until smooth, then divide it into two portions and flatten each into a disc. The dough can be used immediately, or it can be wrapped in plastic and stored in the refrigerator for up to one week. If chilled, let the dough soften at room temperature for 30 minutes before rolling.

Preheat your oven to 350°F and position a rack in the middle of the oven. Prepare a baking sheet by lining it with parchment paper.

Roll out one disc of dough on a floured surface to about ½ inch thick. Dust the dough with flour, flip it over, and roll it again until it’s approximately ⅛ inch thick.

Using a peanut-shaped cutter (or a round cutter), cut out shapes from the dough and transfer them to the prepared baking sheet, spacing them about ¼ inch apart. For decoration, you can gently press a diamond pattern into the tops of the cookies with a bench scraper. Gather any dough scraps, re-roll, and cut additional shapes. Bake the leftover scraps if desired to make cookie crumbs.

Bake the cookies for around 15 minutes, or until they are dry and firm. Let the wafers cool completely on the baking sheet before assembling.

Place the butter, peanut butter, honey, vanilla, and salt in the bowl of a stand mixer. Beat the mixture on low speed until combined, then gradually add the powdered sugar while continuing to mix.

Once all the powdered sugar is incorporated, increase the mixer speed to medium and beat the mixture for about 5 minutes, or until it is light and fluffy. Pause occasionally to scrape down the sides of the bowl to ensure even mixing.

Transfer the creme to a piping bag fitted with a ½-inch plain tip.

Pipe approximately 2 teaspoons of the peanut butter creme onto one half of a cookie, distributing it evenly, especially into the "lobes" if using peanut-shaped wafers.

Top with a second cookie to form a sandwich. Repeat with the remaining cookies until all are assembled.

Allow the filled cookies to chill in the refrigerator for about 15 minutes to set the filling. Store the cookies in an airtight container at room temperature for up to one week or in the fridge for up to a month.