Rose levy beranbaum's best bittersweet brownies

4 ounces European bittersweet chocolate, finely chopped 
           8 tablespoons (1 stick) unsalted butter, cut into pieces 
           1/2 cup granulated sugar 
           2 large eggs, at room temperature 
           1/2 teaspoon vanilla extract 
           1/4 cup all-purpose flour 
           Pinch of salt 
           2 ounces pecans, coarsely chopped (about 1/2 cup) 
           Position a rack in the center of the oven and preheat to 350  
           degrees.  Line the bottom of an 8-inch baking pan with wax paper.   
           Lightly butter and flour the inside of the pan, tapping out  
           excess flour. 
            
           In the top part of a double boiler, over hot, not simmering  
           water, melt chocolate and butter, stirring often, until smooth.   
           Remove from heat and let stand 10 minutes, until tepid.  Whisk in  
           sugar. One at a time, whisk in eggs, then vanilla.  Using a  
           wooden spoon, stir in flour and salt, just until blended.  Stir  
           in pecans. 
           
           Spread batter evenly into prepared pan and bake 20 to 25 minutes,  
           until a toothpick inserted 1 inch from the side of the pan comes  
           out with a moist crumb.  (The center will appear quite wet.)   
           Cool for 20 minutes on a wire rack.  Run a knife around the  
           inside edge of the pan to release the brownie from sides, and  
           invert brownie onto a lightly buttered baking sheet.  Carefully  
           peel off wax paper, invert again onto wire cake rack, and cool  
           completely.  Using a sharp knife, cut into 16 squares.  Wrap each  
           brownie tightly in plastic wrap.