Preheat oven to 350° F degrees.
Spray an 11x7 inch glass baking dish evenly with non-stick cooking spray.
In a large microwave safe bowl add 8 tbsp butter & bittersweet chocolate chunks. Microwave in 15-30 sec intervals for about 1 minute or until melted, stirring occasionally. Remove from microwave.
Gradually add unsweetened cocoa powder. Stirring as you go.
Next, add the light brown sugar and the all-purpose flour. Mix well.
Then, add the vanilla extract, 1 tbsp peppermint extract, eggs, and salt to the bowl. Mix together until everything is smooth.
Fold in ½ cup of mini chocolate chips.
Pour brownie batter into greased baking dish.
Bake for 25 minutes or until toothpick inserted with a few moist crumbs still clinging that look dull, not glossy. Allow to cool completely.
In the meantime, in a large bowl combine frosting, 2 tablespoons butter and peppermint extract. Mix well.
Add in green food coloring 2 drops at a time until you have reached the desired color of green.
Place frosting in fridge to thicken up.
When brownies are cooled and frosting thickened spread brownies evenly with frosting and top with the remaining 1/2 cup mini chocolate chips.
Serve and ENJOY!