Preheat the oven to 350° F. Line a 9×9 pan with parchment paper and set aside.
In the bowl of a stand mixer or in a large bowl with an electric hand mixer, cream together the melted butter, brown sugar, and granulated sugar for 3 minutes.
Next, add in the eggs and vanilla extract, mixing until well combined.
Add in the flour, cocoa powder, corn starch and salt. Mix until the batter comes together.
Pour into the prepared pan and spread smooth.
Bake at 350° F for 20-25 minutes or until a toothpick comes out mostly clean from the center and the temperature reaches 190° in the center.
Allow the brownies to cool completely. Once completely cool, make the mint frosting.
To make the frosting, beat the salted butter at a high speed with either a stand mixer or electric hand mixer for 10 minutes. The butter will be light in color and fluffy in texture.
To the butter add the powdered sugar, clear vanilla and mint extract. Whip for an additional 2 minutes. Add the food coloring a few drops at a time to dye the frosting your desired green. Mix well.
Spread the frosting onto the cooled brownies and refrigerate. While the brownies are in the fridge, make the chocolate ganache.
To make the ganache layer, measure out the chocolate chips in a heat safe bowl.
Microwave the heavy cream for 30 seconds to 1 minute or until the heavy cream is hot and boiling.
Pour the heated cream over the chocolate chips and allow the chocolate chips and cream to sit for 5 minutes while covered with foil.
After 5 minutes, stir to combine. Once smooth, pour over top of the chilled brownies and spread to cover.
Return to the fridge to allow the chocolate layer to set up. Once the ganache has set, cut and serve the brownies.
Enjoy!