Preheat your oven to 350°F (or 325°F if using a dark/nonstick pan) and line a 9-inch square baking pan with foil, greasing it lightly.

Prepare the brownie mix according to the package instructions with water, vegetable oil, and eggs. Pour into the pan and bake for 25-30 minutes. Cool completely on a wire rack for 1.5 hours.

Beat together softened butter and cream cheese until smooth. Gradually add heavy whipping cream, powdered sugar, mint extract, and green gel food color, mixing until fluffy.

Spread the mint filling over the cooled brownie base evenly. Cover and refrigerate for 1 hour to set.

In a saucepan, melt butter, heavy cream, and chocolate chips over medium-low heat, stirring until smooth. Let cool for 15 minutes.

Pour the chocolate topping over the chilled mint layer and spread evenly. Refrigerate uncovered for 2 hours.

Lift the brownies from the pan using the foil and cut into squares. Let sit at room temperature for 20 minutes before serving.