Adjust an oven rack one-third up from the bottom and preheat oven to 425 degrees. Line a 9x13x2-inch metal pan with nonstick foil or parchment paper.Melt the butter in a heavy saucepan. When almost melted, reduce heat to low and add chocolate. Stir until chocolate is very soft, then remove from heat and let chocolate melt in the residual heat of the butter.In the bowl of a stand mixer, beat the eggs with the vanilla and almond extracts, salt, espresso and sugar at high speed for 10 minutes. On low speed, add the chocolate mixture and beat only until mixed.
Remove the bowl from the mixer and stir in the flour and the nuts.
Pour the batter into the prepared pan.
Bake for 35 minutes, reversing the pan from front to back once to ensure even baking (Maida covers her brownies loosely with foil halfway through to prevent burning, but I didn’t). At the end of 35 minutes, the cake will have a firm crust, but when tested with a toothpick will appear underbaked. Take them out anyway.
Remove the pan from the oven and let stand until cool. Invert the brownies onto a cookie sheet and remove the foil. Cover with length of waxed paper and another cookie sheet..invert again. This cake is best covered and refrigerated for a few hours or overnight before it is cut into bars.
