From the America's Test Kitchen Family Cookbook. These brownies look so scrumptious. I can't believe I have had the will power to cut them, and photograph them without eating a single bite. Jesse just had one and told me they were "awesome".
Peanut Butter Swirl Bake Sale Brownies
8 tablespoons (1 stick) unsalted butter.
3 ounces unsweetened chocolate, chopped (do not substitute).
1 cup sugar
2 large eggs
1 teaspoon vanilla
1/2 teaspoon baking powder
1/4 teaspoon salt
2/3 cup all purpose flour
1/3 cup creamy peanut butter - room temp
Put oven rack in the middle position and pre-heat to 350. Line and 8 inch square pan with foil and lightly coat with vegetable oil spray. Melt the butter and the chocolate together in the microwave, stirring often, 1 to 2 minutes. Let mixture cool slightly.
Whisk the sugar, eggs, vanilla, baking powder and salt together in a large bowl. Whisk in the melted chocolate mixture until smooth. Stir in the flour mixture until no streaks remain. Scrape the batter into the pan and smooth the top. Drop the peanut butter in 10 small dollops over the batter. Run a butter knife through the batter to create swirls without touching the foil lining. Bake until toothpick inserted into the center comes out with just a few crumbs, 22 to 27 minutes. Let cool on a wire rack.