Prepare the Brownie Base:

• Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan or line it with parchment paper for easy removal.
• In a mixing bowl, combine the brownie mix with the required eggs, oil, and water as specified on the package. Stir until just combined.
• Pour the batter into the prepared baking pan, spreading it evenly.
• Bake according to the package instructions, typically 20–25 minutes, or until a toothpick inserted into the center comes out clean.
• Remove from the oven and allow the brownies to cool completely in the pan.

Prepare the Mint Layer:

• In a medium bowl, beat together the softened butter, powdered sugar, milk, and peppermint extract until smooth and creamy.
• If desired, add a few drops of green food coloring to achieve a light minty hue.
• Once the brownies have cooled, spread the mint mixture evenly over the brownie layer.
• Place the pan in the refrigerator to allow the mint layer to set, about 30 minutes.

Prepare the Chocolate Ganache:

• In a microwave-safe bowl, combine the semi-sweet chocolate chips and heavy cream.
• Microwave in 30-second intervals, stirring after each, until the mixture is smooth and fully combined.
• Allow the ganache to cool slightly, then pour it over the chilled mint layer, spreading it evenly.
• Return the pan to the refrigerator to set the ganache, approximately 15–20 minutes.

Serve:

• Once the ganache has firmed up, remove the brownies from the pan using the parchment paper overhang.
• Cut into squares using a sharp knife, wiping the blade clean between cuts for neat edges.
• Serve chilled or at room temperature.