In a mixing bowl, whisk together flour, cocoa powder, baking powder, baking soda and salt, set aside. In the bowl of an electric stand mixer, fitted with paddle attachment, whip together butter, granulated sugar, and light brown sugar until pale and fluffy, about 4 minutes.
Add in eggs one at a time, mixing until combined after each addition. Stir in vanilla. Slowly add in dry ingredients and mix until combined.
Transfer dough to an airtight container and chill until firm enough to shape into balls, about 2 hours. Preheat oven to 350 degrees during the last 10 minute of dough chilling.
Remove cookie dough from fridge, scoop dough out and shape into balls, about the size of a golf ball. Transfer rolled balls to Silpat lined cookie sheets and bake in preheated oven 10 - 11 minutes (transfer dough balls that aren't currently baking to refrigerator to chill until ready to bake).
Remove from oven and allow to cool several minutes before transferring to a wire rack. Cool completely then spread frosting along bottom side of one cookie, then sandwich to the bottom side of another cookie. Store in an airtight container.
For the Chocolate Cream Cheese Frosting:
In a mixing bowl, using an electric hand mixer on medium speed, whip together cream cheese and butter until smooth and fluffy, about 1 minute. Add in vanilla and powdered sugar, then sift in cocoa powder and mix until smooth and fluffy, about 1 minute.