adapted from Baked: New Frontiers in Baking and Whitney in Chicago

1 1/4 cup flour

1 teaspoon salt

2 tablespoons unsweetened cocoa powder

11 oz. bittersweet dark chocolate chips

1 cup butter (2 sticks) cut into 1 inch pieces

1 teaspoon instant espresso powder

1 1/4 cups sugar

1/2 cup brown sugar

5 eggs

2 teaspoons vanilla

Preheat the oven to 350.  Butter a 9x13 baking dish.

In a medium bowl, whisk together the flour, salt and cocoa powder.

Put the chocolate chips, butter and espresso powder into a large heat proof bowl.  Place the bowl over a pot of simmering water.  Stir every so often as the chocolate and butter start to melt.  When the mixture is completely smooth, turn off the heat, but leave the pan on the stove.  Stir in the sugars.  Stir until smooth but do not over mix.  Allow the mixture to come to room temperature.

Add 3 eggs to the chocolate mixture and whisk until combined.  Add the remaining eggs and vanilla and whisk until combined.  Sprinkle the flour mixture over the chocolate mixture.  With a spatula, gradually fold in the flour to the chocolate - do not over mix.  Pour the batter into the prepared baking dish.

Bake for 30 minutes.  Let cool completely and cut into squares.  Serve immediately.