1 cup unsifted bleached all-purpose flour
1/2 cup unsifted bleached cake flour
1/2 teaspoon baking powder
1/2 teaspoon salt
3/4 cup miniature semisweet chocolate chips
1 pound (4 sticks) unsalted butter, melted and cooled to tepid
2 ounces bittersweet chocolate, melted and cooled to tepid
8 large eggs
2 1/4 cups superfine sugar
1 3/4 cups firmly packed light brown sugar
4 teaspoons vanilla extract
seeds from 1 small vanilla bean, scraped clean
- Preheat oven to 325 degrees F. Line a 9 x 13" baking pan with foil and lightly spray with nonstick cooking spray.
- Sift together the cocoa powder, all-purpose flour, cake flour, baking powder and salt. Toss the chocolate chips with 3/4 teaspoons of the sifted mixture in a small bowl.
- In a medium-size mixing bowl, whisk the melted butter and melted chocolate until combined.
- In a large mixing bowl, beat the eggs just to mix. Add the superfine sugar and beat for 30 seconds to mix but not add volume. Blend in the light brown sugar.
- Blend in the melted chocolate-butter mixture, vanilla extract and vanilla bean seeds, mixing slowly with a whisk until thoroughly incorporated.
- Add the dry ingredients and whisk slowly into the mixture until just combined, scraping down the sides with a rubber spatula to keep even-textured. The batter will be thick. Fold in chocolate chips.
- Scrape batter into prepared pan and smooth top with flexible palette knife.
- Bake for 40-44 minutes or until just set and a toothpick inserted near the center comes out with a few moist crumbs. Cool completely before cutting and serving.