Preheat oven to 350. Lightly grease a 12 x 17 rimmed baking sheet and set aside.

On the stove or in the microwave combine butter and chocolate and heat until mixture is melted and smooth. Do not overheat. Add sugars and stir until combined.

Whisk in the eggs and vanilla and mix until large bubbles pop at the surface. It should be really glossy and thick.

In a large mixing cup whisk together flour and salt. Add to the batter and mix until few streaks remain. Do not overmix. Brownies do not like that! Stir in chocolate chips.

Spread batter into prepared pan. Bake for about 20 minutes. These are thin brownies. Do not overbake. I would even check at 15 minutes. Halfway through baking lift up the baking pan and drop gently onto the oven rack to release any air bubbles. This makes for fudgier brownies. Do not bake these until the edges are dry. Make sure there is a bit of goo sticking to your testing toothpick.

Let cool in the pan and frost if desired. I chilled them in the refrigerator to cool all the way and then frosted them. I then placed them back in the refrigerator.

While brownies are baking prepare frosting by melting butter. Stir in cocoa. Alternately add powdered sugar and milk, mixing to spreading consistency. Add more milk if needed. Stir in vanilla. About 1 c of chocolate frosting.