Preheat your oven to 350F. Prepare your 9x9 inch pan, line with parchment paper and spray with cooking spray.
Using a mixer, cream together the sugar and butter.
Add in your eggs, one at a time.
Add in the flour and cocoa powder. Mix until completely incorporated, it will be very thick.
Pour into your pan and spread out until it's as even as possible. My grandma taught me to gently tap the bottom of the pan on the floor and it will help even out the batter.
Bake in the oven at 350F for 40-45 minutes. To test, poke a toothpick or cake tester in the middle and it should come out clean.
Dark Chocolate Ganache
While your brownies bake, prepare your ganache.
Put your dark chocolate chips into a large bowl and set aside.
In a small pot, over medium heat, without boiling, heat your heavy cream until it become hot.
Pour your hot cream over your dark chocolate chips and stir until all the chocolate melts and the cream is fully incorporated. Set aside.
Once your brownies come out of the oven, let them cool for 10-15 minutes. Pour your dark chocolate ganache over the brownies and let it cool and set for about an hour.
Once the brownies are cool, store in the refrigerator.