Preheat the oven to 350 degrees.
Line an 8×8 baking pan with parchment paper or aluminum foil. I recommend spraying the pan with cooking spray before lining it with parchment paper (this helps the parchment paper stick to the pan). Set the pan aside.
In a medium-large mixing bowl, add melted butter and granulated sugar. Whisk together (or use a hand mixer) until combined.
Add the eggs, vanilla extract, melted chocolate and salt. Mix until combined.
Add the cocoa powder and mix (carefully) until well combined.
Lastly, add the flour and mix until well-combined.
Pour the mixture into the lined 8×8 baking pan and use a silicone spatula to spread the batter evenly throughout the pan.
Bake for 20-25 minutes, or until a toothpick inserted in the center of the pan comes with just a few crumbs. I prefer to remove the brownies before the toothpick comes out completely clean so that you maintain that fudge-y texture!
Once fully baked, remove the brownies from the oven and allow them to cool to room temperature before adding the mint frosting layer. Put them in the fridge for faster cooling, if desired.