• Preheat oven to 350 degrees. Spray a 9×13 pan with cooking spray and line it with parchment paper then spray again.
• In a large bowl, stir together the melted butter and cocoa powder.  Add the granulated sugar, brown sugar, beaten eggs, vanilla extract, and salt. Mix well.  Add the flour and stir just until incorporated. Do not over-mix.
• Bake for 25-28 minutes. Cool for about 10-20 minutes then place in the freezer for 20 minutes.  While brownies are in the freezer, make the mint layer.

For the Mint Frosting:

• Using an electric mixer, beat the butter for 1-2 minutes until fluffy. Slowly add the powdered sugar, then the milk, and beat until fluffy, about another minute. Add the extract and green food coloring (a drop or two at a time until you reach the desired color of green.) Mix until fully incorporated.
• Pull brownies out of the freezer and evenly frost the brownies. Place back in the freezer for about 20 minutes.
• Place butter and chocolate chips together in a microwave-safe bowl and microwave for 30 seconds at a time. Stir in between every 30 seconds. Be careful not to overheat. Stir until smooth. Pull brownies out of the freezer and drizzle the warm chocolate over brownies and spread smooth with a spatula. Put back in the freezer for another 20 minutes to help the chocolate to set. Cut brownies into squares.