Oreo oh oh ohs

1 1/4 cups (112g) plain flour
1/2 cup (50g) unsweetened cocoa
1 teaspoon baking soda
1/4 teaspoon baking powder
1/4 teaspoon salt
1 cup (192g) sugar
1/2 cup plus 2 tablespoons (115g) room-temperature, unsalted butter
1 large egg
For the filling:
1/4 cup (58g) room-temperature, unsalted butter
1/4 cup (58g) vegetable shortening
2 cups (260g) sifted confectioners’ sugar
2 teaspoons vanilla extract

Preheat oven to 375°F.
In a food processor, or with a wooden spoon, thoroughly mix the flour, cocoa, baking soda and powder, salt, and sugar. Blend in the butter, and then the egg either in food processor or with your hands (the warmth of your hands melts in the butter and makes it come to like a thick, crumbly dough). Continue processing or mixing until dough comes together in a mass.
Take rounded teaspoons of batter and place on a parchment paper-lined baking sheet two inches or so apart. With moistened hands, slightly flatten the dough. Bake for 9 minutes, rotating once for even baking. Set baking sheets on a rack to cool.
To make the cream, place butter and shortening in a mixing bowl, and gradually beat in the sugar and vanilla. Beat for 2 to 3 minutes until filling is light and fluffy.
To assemble the cookies, spread cream onto every other chocolate biscuit. Place another cookie, equal in size to the first, on top of the cream. Lightly press, to work the filling evenly to the outsides of the cookie. Continue this process until all the cookies have been sandwiched with cream. Dunk generously in a large glass of milk. OM NOM NOM