Mint Brownies

Preheat the oven and prep the pan - Arrange a rack in the center of the oven and preheat the oven according to the brownie mix package directions. Lightly spray an 8x8-inch metal baking pan with nonstick cooking spray. Line the pan with parchment paper, leaving an overhang on all sides.

Prepare the brownie layer - Prepare the brownie mix according to the package directions. Scrape the brownie batter into the prepared pan and smooth into an even layer. Bake the brownies according to the package directions for an 8-inch pan. Set the brownies in their pan over a wire rack and allow to cool completely, about 1 hour.

Prepare the mint cream layer - In a bowl with a hand mixer, beat the butter, cream cheese, peppermint extract, and salt on medium speed until smooth and combined, about 1 minute, scraping down the bowl as needed. Sift the powdered sugar into the butter mixture. Add 1 tablespoon heavy cream and green food coloring (if using, start with 3 drops) and beat on medium-low until combined, then increase the speed to medium-high and beat until slightly lightened in color and fluffy, 30 seconds more. Scrape the mint cream over the cooled brownies still in the pan and smooth into an even layer. Refrigerate until the mint layer is set and doesn't stick to your finger when gently poked, 30 to 40 minutes.

Prepare the ganache - Heat 1/3 cup heavy cream in a small, microwave-safe bowl in the microwave in 15-second increments until the cream is very hot and slightly bubbling, 30 to 45 seconds total. Add the chopped semi-sweet chocolate to the cream, ensuring it's all covered, and let sit for 1 minute so the chocolate can begin to soften. Stir the heavy cream and chocolate until the chocolate is fully melted. Let sit about 5 minutes to cool slightly.

Top with the ganache and chopped chocolate mints - Working quickly to avoid melting the mint layer, pour the ganache over the mint cream and smooth into an even layer. If using, sprinkle the chopped chocolate mints over the ganache. Return the brownies to the refrigerator until well chilled and firm, at least 30 minutes. Transfer the slab of brownies using the overhanging parchment onto a cutting board. Use a sharp knife to cut the brownies, wiping the knife clean between each cut. For the best texture and flavor, serve the brownies chilled from the refrigerator. The brownies can be stored in a single layer in an airtight container in the refrigerator for up to 1 week.