Blondies are down-to-earth bar cookies, made from a simple batter whose ingredients you probably already have on hand. Good bakers sometimes overlook these plain confections in favor of something more complicated. A blondie isn’t just a paler cousin of the brownie. With a decent amount of chopped bittersweet chocolate, a blondie has depth and the chunks contrast nicely with brown sugar. The batter, which is mixed in a bowl with a spoon (no mixer!), begins with melted butter, so you are guaranteed moist, chewy squares.
* Butter (for the pan) * 8 tablespoons (1 stick) unsalted butter, cut into chunks * 1 1/4 cups light brown sugar * 1 cup flour * 1/2 teaspoon baking powder * 1/4 teaspoon baking soda * 1/4 teaspoon salt * 2 eggs, lightly beaten * 2 1/4 teaspoons vanilla extract * 1 1/3 cups chopped bittersweet chocolate
source: Lisa Yockelson, Boston Globe, http://www.boston.com/lifestyle/food/articles/2011/05/18/chocolate_chunk_blondies/