Preheat the oven to 350F degrees (180C) and line an 8x8 inch (20x20 cm) pan with parchment paper so that there's an overhang around the edges. Alternatively, lightly grease the pan.

In a medium bowl, whisk together the flour, cocoa, cornstarch and salt. Set aside.

In a separate large bowl, whisk together the melted butter and sugar until you no longer see the butter sitting on top of the sugar.

Whisk in the eggs, red food coloring, vanilla extract and vinegar until smooth and you no lo longer see pieces of egg.

Gently whisk the flour mixture into the wet ingredients. Do this by hand. Stop mixing when you no longer see streaks or lumps of dry ingredients.

Optionally, stir in the chocolate chips.

Pour the batter into the prepared pan and bake for 28-32 minutes, or until an inserted toothpick comes out clean or with a few damp crumbs. If you plan to frost the brownies, I recommend baking them closer to 30-32 minutes so that they aren't too gooey. They will still be chewy and moist.

Cool the brownies in the pan until the pan is no longer warm to the touch.

If frosting, see below. If not frosting, lift the brownies out of the pan using the overhang of the parchment paper. Place on a cutting board and slice with a sharp knife.

In a medium bowl, beat the butter until smooth.

Then add in the chopped cream cheese and beat until smooth.

Add in 1 cup of the powdered sugar along with the vanilla and salt. Mix together starting with the mixer on a low speed.

Beat in the rest of the powdered sugar about ¼ cup at a time until the desired sweetness is reached. If you'd like the frosting to be a little thinner or a little less sweet, beat in 1 tablespoon of cream (you may not need any cream).

If you lined the pan with parchment, lift the cooled brownies out the pan using the overhang and place on a cutting board.

Frost the cooled brownies using a flat edge knife (either in the pan if you just greased the pan or on the cutting board). Optionally, decorate with sprinkles. Slice using a sharp knife.