Bruce Weinstein, . . Morrow, $16.95 (224pp) ISBN 978-0-06-093761-4

As Weinstein and Scarbrough point out in their fun introduction, brownies are an American original, "part confection, part pastry.... the stuff of dreams." It's debatable, however, whether they deserve their own cookbook. The authors attempt to overcome this with chapters dedicated to blondies and concoctions that use packaged mixes, but the results are a mixed batch. Classic desserts such as Cake Brownies and Walnut Brownies are the strongest. Each recipe comes with an almost overwhelming number of suggested variations (toasted pepitás and chopped dried prunes, for instance, may jazz up Banana Brownies). Some variations, such as Mexican Chocolate Brownies, introduce new flavor dimensions, and while brownie purists may turn up their noses at Fat-Free Brownies, they are a thoughtful inclusion. Things get weird, however, with Chile Brownies and Sweet Corn Brownies made with canned creamed corn. Some of the blondies repeat flavors from brownie recipes (Banana Blondies, etc.) or take inspiration from them (Jam Swirl Blondies mimic Marble Cheesecake Brownies), but they do so with different techniques. The chapter on brownie mixes is puzzling: Why would anyone who loves brownies want to use a mix? Here, too, there are occasionally off-sounding flavor combinations, such as Brownie Mix Lemon Bars and Brownie Mix Peach Cobbler. (Sept.)