Recipe from fakeginger.com.
If you love everything peanut butter, you will die for these cookies! Warning: drink with a tall glass of milk!
What you'll need
1 1/2 cups old-fashioned oats
1/2 cup flour
1/2 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
1/2 cup unsalted butter, softened
1/2 cup sugar
1/2 cup brown sugar
1/2 cup creamy peanut butter
1/2 tsp vanilla
2 tbsp butter, softened
1/2 cup powdered sugar
1 cup creamy peanut butter
1-2 tbsp milk or cream
(note: if using natural unsweetened peanut butter for the filling, use 1/2 cup peanut butter and adjust milk according to desired consistency.)
1. Preheat oven to 350°F. Line 2 large cookie sheets with parchment paper.
2. In a medium bowl, whisk together the oats, flour, baking powder, baking soda, and salt. Set aside.
3. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and both the sugars until light and fluffy. Add egg, peanut butter, and vanilla. Pour oat mixture into peanut butter mixture, mixing until just combined.
4. Place rounded teaspoonfuls of batter on the baking sheets, leaving about 2" between each one. Pat dough down so they form small flattened circles. Bake for about 8 minutes or until golden. Let cool on a wire rack.
5. Meanwhile for the filling: beat the butter, sugar and peanut butter until combined. Add milk as needed to achieve desired consistency.
6. To make cookie sandwich, spread a bit of frosting on one cookie, top with another cookie.