In a food processor, pulse the cookies until powdery. Add 2 T cocoa; pulse again. Stir in 1 stick melted butter. Press into bottom of 9x13” dish (no need to grease), using the inside of a butter stick wrapper.
Melt remaining butter over a double boiler. Stir in the sugar and remaining cocoa. Cool slightly. Stir in the peppermint extract. Add the eggs and stir until shiny. Add the flour and fully incorporate.
Pour over the cookie layer. Bake at 350F for 15-20 minutes, or until a toothpick inserted into the brownie layer comes out with wet crumbs (it may seem too wet, but don't worry).
Immediately cover the top with the chocolate. Wait a few minutes, then spread the chocolate into a smooth layer. Sprinkle the candy canes over and gently press into chocolate. Cool slightly before cutting.
If the cookie crust feels really wet and/or there’s not enough to cover the base of the pan, pulse a few more cookies in the food processor, add the dough in the pan back into the food processor, and pulse to combine.
If you're lazy and/or pressed for time: ignore the cookie crust and chocolate/peppermint on top. Crumble the Oreos with your fingers, and stir them into the brownie batter with chocolate chips and peppermint bits. Bake per usual!