Chocolate and Candy Cane Sandwich Cookies

In a food processor, combine the flour, cocoa, baking soda, baking powder, salt, and sugar.
Add the butter and pulse until its incorporated, then add the egg.
Preheat the oven to 375.
Chill the dough for a few minutes in the refrigerator while your oven is preheating.
Take rounded teaspoons of the batter and form them into balls, placed evenly on a parchment lined cookie sheet about 2 inches apart, making sure the balls are round and evenly-sized.
With the heel of your hand, flatten each ball slightly so that they look like chubby disks.Bake for 9 minutes.
Let the cookies cool on the sheet for a few minutes, then transfer to a rack to cool.
Crush the candy canes put the canes in a ziploc bag, bang them with a rolling pin until they were in small pieces, then roll them with said rolling pin until I had candy cane dust/powder.
To make the filling, combine the butter and shortening in a mixing bowl, and add until combined.
Slowly beat in the powdered sugar until incorporated.
Add the extract, beat until combined, then add your candy cane dust and stir until just combined.
To assemble the cookies, try to match up your cookies with a pair of roughly equal size and shape.
Place the filling in a pastry bag and, using a 1/2 inch pastry tip, pipe a small blob of filling right in the center of one of your cookies.
Using the other half of the sandwich, press the halves together until the filling has spread to the edge, or nearly.
Repeat for the remaining sandwiches.