Preheat the oven to 350°F degrees. Line 9x13 baking pan with foil and spray with non-stick cooking spray or line with parchment paper.
Place the flour, cocoa powder, baking soda, salt, and both sugars into the bowl of a stand mixer with the paddle attachment. Mix on low until combined.
In a microwave-safe bowl, add in the butter and break up the semi-sweet chocolate bar, and place on top. Heat on High in the microwave for one minute and stir. Heat for an additional minute in the microwave, let sit for one minute and stir to combine. Repeat only if necessary, everything should be melted. Stir in the vanilla and let sit on the counter for 5 minutes to cool.
While the mix is cooling, add the eggs to the mixer bowl with the dry ingredients one at a time. When all the eggs are added, beat on medium speed for two minutes. Turn the mixer down to low and slowly pour in the liquid mix, beat until fully incorporated but do not over mix.
Add the chocolate chips and fold them into the brownie mix.
Scoop half of the brownie mix into the pan and smooth it out with a spatula.
Layer on the mint oreo cookies.
Then top with remaining brownie batter, and smooth out.
Bake for 20-23 minutes until the top is shiny and set, take it out of the oven, and let cool on a wire rack.
Mint Frosting:
With a hand mixer, whip the butter on medium speed in a medium-sized bowl for 2 minutes. Add in the powdered sugar a little at a time until fully combined. Add in the milk and whip for an additional 2 minutes on high speed.
Add in the peppermint extract and food coloring to the color you want. Whip one additional minute.
Spread on the mint frosting once the brownies have cooled. Place in the refrigerator to set for one hour.
Milk Chocolate Fudge Frosting:
Place the butter in the bottom of a microwave-safe bowl. Place the milk chocolate chips on top of the butter.
Pour the sweetened condensed milk on top of the chocolate. Heat in the microwave on high for 1 minute. Let sit for 1 minute and stir.
Repeat again and a third time only if necessary. The mixture should combine fully and be melted.
Pour on top of the fudge frosting and carefully smooth it out. Place back in the refrigerator until ready to serve to let the frosting set. Enjoy!
Notes
Make sure you use unsweetened cocoa powder and not dutch process.
We like to use high quality chocolate chips for this recipe.
Different types of mint cookies can be found at different grocers, you don't need the oreos.
These can be frozen, see my storage tips above!
These need to be refrigerated as well because you don't want the frosting to melt off.
Make sure your brownies are fully cooled before you frost them.