2 sticks (8 ounces) unsalted butter, cut into 16 pieces
9 ounces bittersweet chocolate, coarsely chopped (we used Ghirardelli 60% bittersweet chips)
1 1/2 cups/150 grams sugar (we cut it back to 125 grams)
4 large eggs
2 teaspoons pure vanilla extract
1 tablespoon instant espresso powder (optional)
1/2 teaspoon salt
1 cup/140 grams all-purpose flour
3/4 cup pecans, chopped (my choice, optional)
Getting Ready: Center a rack in the oven and preheat the oven to 325 degrees F. Line a 9-x-13-inch baking pan with foil, butter the foil and place the pan on a baking sheet. (we used parchment paper, which doesn't need buttering)
Set a heatproof bowl over a saucepan of simmering water. Put the butter in the bowl, top with the chopped chocolate and stir occasionally until the ingredients are just melted - you don't want them to get so hot that the butter separates. Remove the bowl from the pan of water.
With a whisk, stir in the sugar. The mixture might get grainy, but it will even out. Whisk in the eggs one by one, then add the vanilla and whisk enthusiastically to smooth the batter. Finally, gently whisk in the espresso powder, if you're using it, salt and flour, stirring only until incorporated. Scrape the batter into the pan and smooth the top with a rubber spatula. Sprinkle the pecans (if using) on top of the batter and lightly press into the batter, just enough to set so the nuts don't fall off when the brownies are sliced.
Bake the brownies until the top is dull and a knife inserted into the center comes out clean, usually about 40 minutes. Transfer the pan to a rack and cool the brownies to room temperature.
When they are completely cool, turn out onto a rack, peel away the foil and invert onto a cutting board. Cut into 32 slender rectangles, each roughly 2 1/4 x 1 1/2 inches.