Preheat oven to 350. Prep a 9x13 baking pan with parchment cradle. Spray with non-stick spray.

In a glass bowl microwave the bittersweet and unsweetened chocolate with the butter, in 30 second increments, stirring until the mixture is smooth. Let cool until lukewarm

Stir in sugar, salt and vanilla. Add the eggs 1 at a time, stirring well after each addition.

Stir in flour just until the mixture is just combined. Stir in the chocolate chips.

Pour the batter into a well-buttered and floured 13- by 9-inch baking pan, smooth the top, and bake the mixture in the middle of a preheated 350°F oven for 25 to 30 minutes, or until a tester comes out with crumbs adhering to it. Let the mixture cool a bit in the pan on a rack then slide the parchment and brownies ouit onto counter. Cut it into 24 bars.

Note: Before baking I topped the batter in the pan with 1 cup of chopped pecans and about1-1/2 cups mini marshmallows. Pressed them down into the batter slightly. Turned out great! This is not a very sweet brownie batter so the marshmallow topping added a nice sweetness.