- 3/4 pound bittersweet chocolate, coarsely chopped
- 2 sticks unsalted butter, cut into small pieces
- 1 teaspoon instant espresso, diluted in hot water
- 1 1/2 cups all-purpose flour
- 1 teaspoon baking powder
- 1/2 teaspoon salt
- 4 large eggs
- 2 cups granulated sugar
- 1 teaspoon vanilla extract
- 2 cups coarsely chopped walnuts
- Position rack in center of oven and preheat oven to 350 degrees. Butter, or coat with vegetable spray, an 8-inch square baking pan.
- Dust with flour, tapping out excess flour.
- Set aside.
- In the top of double boiler or medium heatproof bowl set over simmering water, combine chocolate, butter, and espresso (if desired), stirring occasionally until almost melted.
- Turn off the heat, stir, and let melt completely.
- Sift together the flour, baking powder, and salt. Set aside.
- In a large heatproof mixing bowl set over simmering water, whisk the eggs, sugar, and vanilla until the sugar dissolves.
- Transfer to the large bowl of an electric mixer, on high speed, using paddle or beaters, beat until pale yellow.
- Lower speed to medium, scrape in the chocolate mixture, and beat until well mixed.
- On low speed, gradually add flour mixture and beat just until combined.
- Add 1 cup of walnuts and again, on low speed, beat just until combined.
- Scrape into prepared pan and sprinkle remaining walnuts over top of cake.
- Bake until edges of cake pull away from sides of pan and a toothpick inserted into center of cake comes out clean, 40 to 45 minutes.
- Cool on wire rack.
- To serve, cut the brownies into 9 squares, each about 2 1/2 inches.
- Serve as is or with softly whipped cream or ice cream of your choice.