Old-Fashioned Brownies with Chocolate Cream Cheese Frosting

Preheat the oven to 350 degrees Fahrenheit. Prepare a 9x13 baking dish with parchment paper. Set aside
In a mixing bowl, whisk together the melted butter and sugar until creamed. About two minutes. Gradually add in the eggs one at a time as you whisk. Then add the vanilla extract.
Add the flour to the bowl, taking breaks to mix it in the batter with a spatula. Add the cocoa powder. Mix the batter with the spatula, making sure to scrape the side of the bowl to incorporate all the ingredients. Fold in the chocolate chips, if adding them.
Bake the brownies for 23-28 minutes. To check if they're done, stick a toothpick in the center of the brownies. If they still have wet batter on them, they aren't quite done. If the toothpick has moist crumbs on them, they're ready to come out of the oven. Allow to cool for 30 minutes before frosting.
To make the frosting, cream the butter and cream cheese with a hand mixer for about two minutes. Mix in the vanilla extract. Add the cocoa powder. Gradually add the powdered sugar, while mixing. Stop to scrape the sides of the bowl as you add the ingredients. Finally, mix in the heavy cream or milk.
Once the brownies are cooled, frost them. Serve immediately after frosting, or put them in the fridge, making sure to take them out an hour before serving.