Here is the recipe as posted on Smitten Kitchen with my notes in bold:
1 cup (4 ounces) pecans or walnuts, chopped medium (optional). I am not a fan of nuts in most baked goods. Baklava, yes. Brownies, no.
1¼ cups (5 ounces) cake flour. I used regular flour. It didn't seem to make any difference.
½ teaspoon salt
¾ teaspoon baking powder
6 ounces unsweetened chocolate, chopped fine. I used Baker's Chocolate and actually only realized just now that I was supposed to chop it. Seemed fine.
12 tablespoons (1½ sticks) unsalted butter, cut into six 1-inch pieces
2¼ cups (15¾ ounces) sugar. This is a lot of sugar. Make sure you have enough!
4 large eggs
1 tablespoon vanilla extract. This seemed like a lot to me, but I am always on board with vanilla.
1. Adjust oven rack to middle position; heat oven to 325 degrees. Cut 18-inch length foil and fold lengthwise to 8-inch width. Fit foil into length of 13 by 9-inch baking dish, pushing it into corners and up sides of pan; allow excess to overhand pan edges. Cut 14-inch length foil and, if using extra-wide foil, fold lengthwise to 12-inch width; fit into width of baking pan in same manner, perpendicular to first sheet. Spray foil-lined pan with nonstick cooking spray. There was no cooking spray, so I used oil.
2. If using nuts, spread nuts evenly on rimmed baking sheet and toast in oven until fragrant, 5 to 8 minutes. Set aside to cool. No nuts for me.
3. Whisk to combine flour, salt, and baking powder in medium bowl; set aside.
4. Melt chocolate and butter in large heatproof bowl set over saucepan of almost-simmering water, stirring occasionally, until smooth. (Alternatively, in microwave, heat butter and chocolate in large microwave-safe bowl on high for 45 seconds, then stir and heat for 30 seconds more. Stir again, and, if necessary, repeat in 15-second increments; do not let chocolate burn.) I went for the stove top method and all went smoothly, even with large squares of chocolate. When chocolate mixture is completely smooth, remove bowl from saucepan and gradually whisk in sugar. Add eggs on at a time, whisking after each addition until thoroughly combined. Whisk in vanilla. Add flour mixture in three additions, folding with rubber spatula until batter is completely smooth and homogeneous.
5. Transfer batter to prepared pan; using spatula, spread batter into corners of pan and smooth surface. Sprinkle toasted nuts (if using) evenly over batter and bake until toothpick or wooden skewer inserted into center of brownies comes out with few moist crumbs attached, 30 to 35 minutes. Mine took 30 minutes and the knife was totally clean when I took it out. They were still moist. Cool on wire rack to room temperature, about 2 hours, then remove brownies from pan by lifting foil overhang. Cut brownies into 2-inch squares and serve.