Preheat oven to 350° and line an 8 x 8 metal baking pan with parchment paper then spray with a nonstick cooking spray. *If using glass, reduce temperature to 325° and cook for an extra 10 minutes.
For The Brownies
In a medium bowl, beat butter and sugar until fluffy, then add vanilla and eggs and beat until combined.
Add flour, baking powder and cocoa, beat until smooth.
Pour into prepared pan. Place in the oven and bake for 25- 30 minutes.
Let cool completely before frosting.
For The Mint Frosting
In a medium bowl, beat butter, powdered sugar, milk, and mint extract until fluffy.
Add green gel food coloring until desire color is obtained.
Spread frosting over the top of brownies.
Sprinkle chocolate chips over frosting, cut, and enjoy.