01 -
Preheat oven to 350°F and line a baking sheet with parchment paper.
02 -
In a large bowl, beat together softened butter, peanut butter, granulated sugar, and brown sugar until smooth and creamy.
03 -
Incorporate the egg and vanilla extract into the mixture, beating until fully combined.
04 -
Whisk flour, baking soda, and salt in a separate bowl until evenly blended.
05 -
Gradually add dry ingredients to the wet mixture and mix until just combined, avoiding overmixing.
06 -
Drop tablespoon-sized portions of dough onto prepared baking sheet, spacing them 2 inches apart.
07 -
Lightly flatten each dough ball with a fork, making a crisscross design.
08 -
Bake for 10 to 12 minutes until edges turn golden. Let cool on the baking sheet for 5 minutes before transferring to a wire rack.
09 -
In a bowl, beat together peanut butter, softened butter, powdered sugar, and vanilla extract until smooth.
10 -
Add milk one tablespoon at a time until the filling reaches a spreadable consistency.
11 -
Spread filling on the flat side of half the cookies, then top with remaining cookies to form sandwiches.
12 -
Sprinkle granulated sugar over the filled sandwiches just before serving, if desired.