The “bread” part of these sandwiches is a very thin, crisp wafer that holds up well to the creamy filling. They taste best when the cookie remains crisp, so fill them just before serving. If you hold them for too long in the refrigerator or at room temperature, these peanut butter cookies will soften and break apart.
For the wafer cookies:
Preheat the oven to 350 degrees.
Line 2 baking sheets with nonstick silicone baking sheets or parchment paper. (Alternatively, use nonstick baking sheets or lightly butter conventional baking sheets.) Set aside.
Place the butter in the bowl of a standing electric mixer fitted with the paddle.
Begin beating on low speed. Add the sugar, increase the speed to medium, and beat for about 4 minutes, or until light and fluffy.
Add the eggs, one at a time, beating to incorporate.
With the motor running, slowly add the oats and salt, beating to combine. When blended, beat in the vanilla followed by the peanuts, beating until incorporated.
When the dough is just blended, remove the bowl from the mixer and scrape the paddle clean.
Using your hands, roll the dough into balls about the size of a large walnut. Place the balls about 2 inches apart on the prepared baking sheets. Working with one cookie at a time, press down on each ball with the bottom of a drinking glass to form a disk about ⅛ inch thick.
When all of the cookies have been made, place in the oven and bake for about 8 minutes, or until golden brown. The cookies should spread quite a bit and be completely browned. Don’t fret if the edges get dark brown; they will be trimmed off.
Remove from the oven and, using a 3-inch round biscuit cutter, and immediately cut each cookie to remove the darker edge and make a neat circle. Using a metal spatula, transfer the cookies to wire racks to cool completely.
Store, airtight, at room temperature for up to a week.
About 15 minutes before serving, spread about 2 tablespoons of the peanut butter filling on the flat side of a cookie. Top with a second cookie, flat-side down, and press together gently.
For the peanut butter filling:
Combine the peanut butter and butter in the bowl of a standing
electric mixer fitted with the paddle. Begin beating on low speed. Add the honey, increase the speed to medium, and beat for about 3 minutes, or until light and fluffy.
Store, airtight, in the refrigerator for up to a week.