For the brownies:
3/4 cup unsalted butter
1 pound bittersweet chocolate, coarsely chopped
1 cup minus 2 tablespoons all purpose flour
5 large eggs
2 cups light brown sugar
1/2 teaspoon salt
1 teaspoon vanilla extract
Preheat the oven to 350°F. Line a 9″x13″ glass baking dish with parchment.
In a small saucepan, melt the butter over low heat. Remove from the heat and stir in the chocolate. If the heat from the butter does not fully melt the chocolate, put the pan back over the heat for 10 seconds and stir until melted. Set aside to cool.