Preparation:
Preheat oven to 350 degrees.

Spray a 9-inch square pan and line with parchment paper.

In a double boiler, melt the butter and bittersweet chocolate together, staring often. Once melted, set aside.

In a large bowl, whisk both sugars, the eggs and yolks. Whisk the salt and vanilla. Add the melted butter and chocolate and whisk just until combined.

Gradually stir in the flour and mix until everything is combined and smooth. Stir in the chocolate chips.

Scrape the batter into the prepared pan and bake for 35 to 45 minutes, or until toothpick inserted in the middle shows a little goo.

Let the brownies cool in the pan for about 45 minutes.

When completely cool, cut into squares.