1. Preheat the oven to 350 degrees F and grease a 9×13 inch pan or line with aluminum foil or parchment paper. You can also use a 9×9 inch pan for a thicker brownie (requires more cooking time). Set aside for later.

2. In a microwave-safe bowl, combine the butter and 2 ounces of chopped chocolate. Melt in 30 second increments, whisking after each, until completely combined. Whisk in the sugar until completely combined, then whisk in the eggs and vanilla.

3. Add the cocoa powder, flour, salt, remaining 2 ounces of chopped chocolate and the chocolate chips. Fold it all together with a rubber spatula or wooden spoon. Batter will be very thick. Spread evenly into prepared pan.

4. Bake for 30 minutes, then test the brownies with a toothpick. Insert it into the center of the pan. If it comes out with wet batter, the brownies are not done. If there are only a few moist crumbs, the brownies are done. Keep checking every 2 minutes until you have moist crumbs. They should take 30-33 minutes in a 9x13in pan or 40-45 mins in a smaller pan.

5. Remove from the oven and place on a wire rack to cool completely in the pan before cutting into squares.

6. Cover and store leftover brownies at room temperature.