Cookie Monster - DIY oreos

I'm squeezing in a lot of posts here at the end of the year.
I know it's not Wednesday, but I wanted to squeeze in one more cookie recipe before everyone starts their New Year's resolutions.
I made these cookies for my cousin, who was also M's best friend for Christmas.  I wanted to make him an extra special treat, so this is what he got.
The frosting for these cookies is spot on - delicious!  I want to use it to frost some more cookies in the future, not just to use as filling for these oreos.

DIY Oreos
Ingredients

• 1 1/4 cup flour
• 1/2 cup unsweetened Dutch process cocoa powder
• 1 teaspoon baking soda
• 1/4 teaspoon baking powder
• 1/4 teaspoon salt
• 10 Tablespoons (1 1/4 sticks) unsalted butter, at room temperature
• 1 large egg

Directions

Using a mixer, combine the flour, cocoa powder, baking soda, baking powder, salt, and sugar.  Mix briefly to combine.  Add the butter to the bowl and mix briefly.  Add in the egg and mix until the dough forms a cohesive mass.

Scoop a Tablespoon of dough onto a cookie sheet lined with parchment paper or a silicone baking mat.  (I used my cookie scooper for this, but I would have liked to use a smaller size as some of my oreos turned out pretty monstrous).

Gently press down on the dough balls to flatten slightly

Bake for 9-11 minutes at 375 degrees, rotating the pans halfway through.  Let cool some before removing cookies to a cooling rack to finish cooling.  The cookies must be 100% cooled before filling.

Frosting
Ingredients

• 4 Tablespoons (1/4 cup) room temperature unsalted butter
• 1/4 cup vegetable shortening (Crisco)
• 2 cups powdered sugar
• 2 teaspoons vanilla extract

*Note, most times I only make half of a recipe for frosting, because usually the full recipe is way to much for the number of cookies that I ended up with.  But make the full recipe for the oreos.  Trust me.

Directions

Combine the butter and shortening and beat on a med/high speed until smooth.  Add the powdered sugar and slowly incorporate it.  Then increase speed and beat until light and fluffy, 2-3 minutes.  Blend in the Vanilla Extract.

Pair the cookies up by size.  Use a pastry bag fitted with the large pain rough tip to pipe the filling onto one side of the cookie.  Sandwich together and press down/twist to cause the filling to spread out to the edges of the cookie.  If you don't have a pastry bag, you can also use a knife or the back of a spoon to spread the filling onto the cookies.

Recipe from Annies Eats