Preheat the oven to 350F degrees. Line the bottom of a round 9-inch cake pan with parchment paper (or spray with a nonstick baking spray - like Baker's Joy.)
Break the cookie dough into chunks and press them evenly in the bottom of the prepared pan.
Bake the cookie for 20-25 minutes or until the top is just starting to turn golden brown. Remove from the oven then run an offset spatula or butter knife around the edge of the cake pan to stop the cookie sticking while it sets.
Allow the cookie to cool for 15 minutes in the pan before transferring to a wire rack to finish cooling completely.
Spread the frosting over the top of the cooled cookie using an offset spatula or butter knife.
While the frosting is still wet, cut the cookie into 8 slices like a pizza. Clean the knife after each cut to ensure to keep the cookies bars clean.
Add two pretzel halves to the top of the larger end of each slice to create the reindeer antlers.
Add a red or brown M&M at the bottom narrow end of each slice to create the nose.
Finally add two eyes about ⅓ of the way down each slice.
Allow the frosting to fully set before serving.
Notes
You can make your own homemade cookie dough if you'd like.
Other cookie dough can be used like sugar, peanut butter and chocolate.
Make sure that you run a knife around the pan after it comes out of the oven so it does not stick.