Preheat oven to 350F. Line 9×13 inch pan with foil, spray with cooking spray; set aside. Alternately, use a 9-by-9-inch pan for thicker brownies, which is my preference. I don't usually use the foil I like my glass baking dishes.
2Microwave chocolate and butter in large microwaveable bowl for 90 seconds or until butter is melted. Stir until chocolate is completely melted and smooth. Stir in sugars. Stir in eggs and vanilla. If adding espresso or coffee, add it now; batter will be a bit granular and that’s okay. Stir in flour until just combined, do not over mix. Pour into prepared pan.
3Add the Nutella to the top of the brownie mixture and either just leave it sit on top or marble it with a knife in a zig-zag pattern.
4Bake for 25 to 28 minutes, or until edges pull away from the side of the pan and top and center have just set. Keep these gooey and don’t over bake; brownies will continue to firm up as they cool.
5Minty Layers -
In medium bowl, stir together marshmallow fluff, mint extract* (be very careful and do not use more than this unless you love mint; a little bit of mint goes a very long way), 4 drops of food coloring, or until your green is achieved.
6Mix in vanilla frosting and melted white chocolate chips. Spread across the cooled brownies.