Heat oven to 350 degrees. Line a 13x9 inch pan with foil and spray lightly with cooking spray. Set aside.
In a microwave-safe bowl, melt butter and chocolate 30 seconds at a time until melted and smooth. Stir in sugar vanilla and salt. Add in eggs and flour. Mix until incorporated.
Spread brownie mix into the bottom of your 13x9 inch prepared pan. Bake for 40-45 minutes or until toothpick comes out clean. Remove and let cool.
To make the mint frosting layer:
Beat the butter and the cream cheese together. Add in the mint extract, food coloring, and powdered sugar. Beat until smooth and creamy.
Spread on top of the cooled brownies and put in the fridge for 30 minutes to chill.
To make the chocolate ganache:
In a medium sized microwave safe bowl add the butter and the chocolate chips. Melt in the microwave stirring 30 seconds at a time until smooth. Spread on top of mint frosting layer. Chill 1-3 hours until chocolate has set and brownies can easily be cut.