3/4 cup unsalted butter, softened
1/2 cup peanut butter
2/3 cup packed brown sugar
1/2 cup granulated sugar
1 large egg
2 teaspoons baking soda
1 teaspoon baking powder
1 1/2 teaspoons vanilla extract
1 1/4 cups coarsely ground old fashioned oats (toast them for more flavor)
1 cup all purpose flour
1/4 cup unsalted butter, softened
1/4 cup creamy peanut butter
1/2 cup + 1/3 cup confectioners' sugar
Heat oven to 350 degrees F. Coat cookie sheets with cooking spray.
To make the cookies, in a large mixing bowl, using a mixer on medium speed, beat together butter, peanut butter, brown sugar and granulated sugar until creamy - about 3 minutes. Beat in egg, baking soda, baking powder and vanilla until combined. Beat in oats and flour until just combined.
Drop rounded spoonfuls of dough onto cookie sheets, spacing about 2 inches apart. Bake 10-12 minutes, or until golden brown. Cool cookies on sheet for 5 minutes, before transferring to wire racks to cool completely.
To make the filling, in a large bowl, using a mixer on medium speed, beat together butter, peanut butter and confectioners' sugar until well combined and creamy - about 2 minutes. Spread filling in between cookies.
Makes about 12 big cookies