Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, leaving an overhang. Follow package directions to prepare the brownies—do not add the fudge packet if it came with your brownies (save it for later). Very finely chop 6 Oreos and add to the brownie ingredients. Stir everything together to get a thick brownie batter. Transfer to the prepared pan and bake according to package instructions. Don’t overbake. As soon as brownies are baked, remove from oven and allow to cool 3–4 minutes. If you had a fudge packet, spread it over the brownies here. Cover brownies tightly and place in the fridge (or freezer) while preparing frosting layer.
In a large bowl, beat together room-temperature cream cheese and butter until smooth and creamy. Add peppermint extract (to preference; I use 1 teaspoon; see note 1). Add salt, optional food coloring, and powdered sugar. Beat until smooth and creamy. It will seem like it’s not coming together at first, but just keep beating until it does. Scrape the sides as needed with a spatula. Spread frosting evenly over completely cooled brownies. Return brownies to the fridge while preparing the topping.
Topping: In a microwave-safe bowl, combine chocolate chips and coconut oil. Microwave in 20-second bursts, stirring in between, until fully melted and smooth. Pour over the frosting and smooth into an even layer. Let set at room temperature.
Once topping is firm, use the parchment overhang to lift the brownies from the pan. Cut with a sharp knife, running the blade under hot water and drying between cuts for clean slices. Let sit at room temperature for about 30 minutes before serving.
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Notes
Note 1: The strength of the extract varies from brand to brand; I use McCormick® peppermint extract, and 1 teaspoon is perfect. Taste the frosting and decide if you'd like more extract, up to 1 and 1/2 teaspoons.Storage: Store leftover Peppermint Brownies in an airtight container at room temperature for up to 3 days or in the fridge for up to a week. For longer storage, freeze unfrosted brownies in a single layer, then transfer to a freezer bag for up to 3 months. Frost after thawing.