All you need is:
Oreos or President Choice "Eat the Middle First" candy cane flavoured cookies
Follow directions on the brownie box (or use your own recipe) and cover the bottom of the tin or paper liner with some mix then add a cookie and cover with more mix. Bake as directed on box.
1 cup of icing sugar
2-3 tsp of milk (or more to get a good drizzling consistency)
1/4 tsp peppermint or mint extract
For more stuffed brownie ideas... you can look at these neat sites:
This recipe has also been linked up to http://cookiesxo.blogspot.com/2011/11/happy-wonka-wednesday_16.html