1-Let’s dive into baking High Altitude Mint Oreo Fudge Brownies with a simple guide that’s easy to follow, even if you’re new to high-altitude cooking. Start by preheating your oven to 350°F (175°C) and getting your 8-inch square baking pan ready grease it with baking spray or line it with parchment paper for fuss-free removal later. This step sets the stage for brownies that come out just right without sticking.

2-In a large bowl, mix your brownie batter as per the standard instructions, keeping in mind how high altitudes might need a bit more attention to texture. Once baked, let the brownies cool completely, which takes at least 6 hours; speed this up by cooling at room temperature for 1 hour and then chilling in the fridge for 1.5 hours. For the peppermint Oreo buttercream, beat 1/2 cup (113g) of softened unsalted butter with an electric mixer until it’s smooth, about 1 minute.

3-Next, on low speed, add 1 cup (120g) powdered sugar, 1/8 teaspoon coarse kosher salt, 1/2 teaspoon vanilla extract, 1/4 to 1/2 teaspoon peppermint extract, and 2 drops of mint green gel food coloring if you want that fun color. Crank it up to medium speed and beat for a few minutes until it’s light and fluffy, then gently fold in 3 finely chopped chocolate sandwich cookies. Spread this over your cooled brownies evenly. For a refreshing side, pair with a simple ice cream to make your dessert even more special.

4-Now for the chocolate ganache: Put 3 ounces (85g) of finely chopped dark chocolate in a heatproof bowl. Heat 3 ounces (85ml or 6 tablespoons) of heavy whipping cream in a small saucepan until it just starts to simmer around the edges. Pour it over the chocolate, let it sit for 3 minutes, and stir gently until smooth. Pour this over the buttercream and spread it out nicely.

5-Let the ganache cool for 15 minutes, then decorate with mint chocolate candies and chopped chocolate sandwich cookies. For clean slices, wait a few hours for everything to set or pop them in the fridge for 30 minutes. If you’re in a hurry, cut while warm, but decorate first so you can slice between the candies without any mess. Total time is about 1 hour 5 minutes, plus cooling, making it a great option for busy evenings.