The reason so many “;healthy”; treats end up failing to taste like dessert comes down to a combination of careless technique and flawed expectations.

Take the simple butter cookie: It is never going to taste right without butter. Nor will a pie crust have that characteristic crunchy, flaky texture without some combination of white flour and a solid fat. Trying to make a fluffy iced dobash cake out of whole-wheat flour and tofu is a recipe for disappointment.

That's because baking, far more than cooking, relies on a precise chemistry of ingredients—as anyone has discovered who tries to simply cut a cake recipe in two. Sugar, butter and cream don't only affect taste; their interactions are responsible for the texture, browning, spreading and rising of cookies, cakes and pies.

That's why it's easiest to convert baked goods that offer multiple types of pleasure from the start, so you can exchange sweetness and fat for flavor and texture. Think ginger snaps, carrot cake, banana bread or apple crumble.

It's also best to begin tinkering with any recipe conservatively, by substituting no more than half of the fat or sweetener to see what results. You can start by simply eliminating a third of the sugar, and a quarter of the fat, from most traditional recipes without greatly affecting the finished product.

SWEET SUBSTITUTES

Beyond that, simply cutting back on sugar or fat will probably lead to an unpleasant baked surprise. Careful substitutions are needed to approximate the texture and taste of the original.

Consider sweetness. Honey, maple syrup and barley malt syrup are all sweeter than sugar, so you need only 3/4 cup to replace each cup of sugar (especially if you want to retrain your sweet tooth, which is where artificial sweeteners do more harm than good).

Molasses and brown rice syrup, on the other hand, are a lot less sweet, so you'll need 1/3 to 3/4 more, by volume, to replace sugar. These sweeteners also add liquid, so cut back elsewhere in the recipe.

Honey, maple syrup and molasses also are acidic, so it helps to add baking soda as a neutralizer—1/4 teaspoon per cup for honey and maple syrup, 1 teaspoon for molasses.

Brown sugar and other dry sweeteners such as turbinado and Sucanat (unrefined forms of sugar cane) measure and pour just like sugar, but have a stronger molasses taste and may burn more quickly. Whenever you replace sugar, keep a close eye on the baking time and/or reduce the temperature by 25 degrees to prevent overbaking.

None of these sugar substitutes can be called nutritional powerhouses on their own, but they do contain more vitamins and minerals than refined sugar, and enter the bloodstream more slowly. Just remember to match their more distinctive flavors to the baked good in question.

TRICKING THE TONGUE

Fats such as butter, oil and shortening are responsible for making baked goods tender and moist, so substitutions tend to be less satisfying than for sweeteners, which do still manage to sweeten.

Happily, fats are less damaging to the body than sugars and starches, in moderation, and contribute to feeling full. So it makes sense to keep fat substitutions to no more than half the total, and work on introducing more wholesome substitutes for white sugar and flour.

One of the more successful stand-ins for butter or oil is a puree of fruit or squash, such as applesauce, prunes blended with water, bananas, pumpkin or sweet potato (available canned) or butternut squash. These all help create a moist texture, and can sometimes replace all the fat, as well as some of the sweetener.

Reducing the fat content makes goods bake faster, so cut the baking time or temperature by 25 percent, and use a toothpick to test for doneness. The more fat you replace in a recipe, the more you need to guard against toughness, taking steps such as: cutting the number eggs by up to half if all the fat is replaced (not necessary with fruit purees), mixing minimally to prevent the development of glutens, or using a softer (more finely milled) flour.

Lower-fat goods also spoil more quickly, so be sure to refrigerate after one day.

It's tricky to replace butter or shortening in pastries and pie crusts, where the solid fat helps to create the flaky texture—margarine and other substitutes contain too much water, and are usually worse for your health anyway than butter or lard. In cakes, creaming butter and sugar together creates volume, so you might have to add whipped egg whites for low-fat cakes to rise properly.

Lower-fat dairy products (yogurt, half-and-half, cottage cheese, ricotta or evaporated milk, boosted with powdered milk) can stand in for some butter and heavy cream in cakes and quick breads, but read the labels carefully for artificial ingredients. You're better off getting the energy and nutrition from genuine butter or cream than eating mystery chemicals that encourage storage as fat.

Neufchatel is a good example of a healthful substitute: It's a natural type of low-fat cheese, rather than a chemically engineered improvisation. Use Neufchatel for up to two-thirds of the cream cheese in a cheesecake to create the lighter-textured version that many islanders prefer.

All these dairy products substitute more successfully if you use low-fat versions rather than non-fat—the caloric savings hardly justify the loss of quality. If you have time, let them drain for an hour in a strainer to remove excess liquid.

Humble cottage cheese might be the most versatile substitute in desserts, believe it or not. Cookbook author Maida Heatter created a sensation in the low-fat dessert world with her “;Top Secret,”; an all-purpose substitute for cream cheese, mascarpone, sour cream and even ice cream. Basically, it's large-curd 4 percent fat cottage cheese processed on high speed for a full minute, then sweetened and refrigerated for several hours. Fans swear you cannot tell the difference.

NUTRITION WITHOUT BULK

The conventional wisdom has been that you can exchange only half the white flour in a recipe with whole wheat; any more will produce dense, dry results. Finely milled flours are available now, however, that let you substitute one to one: whole-wheat pastry, whole-wheat bread and a product called “;white”; whole-wheat flour can be used to replace 100 percent of the same type of white flour.

Just as with other substitutions, whole grains require some care to prevent the hockey-puck syndrome: Sift whole wheat flour twice to introduce more air, add more wet ingredients if the batter seems dry, shorten the baking time, and mix as briefly as possible.

If you prefer cakes and cookies that are closer to their original taste and texture, stick to just half whole wheat.

The less fluffy and white your baked treats, the less likely to cause the insulin surges that lead to chronic inflammation of the tissues, the root of so many health problems. But eating wholesome desserts will not keep you from gaining weight—or ingesting just as many carbohydrates—if you eat twice as many.

As the Mad Hatter said to Alice, who protested that she could not take “;more”; of something she had not even eaten: “;You mean you can't take less; it's very easy to take more than nothing.”;

Amazing Black Bean Brownie Recipe

Adapted from “;Baking with Agave Nectar,”; by Ania Catalano (Celestial Arts, 2008, $15.95)

3- to 4-ounce high-quality dark chocolate bar
1/2 cup (1 stick) butter
2 cups cooked black beans, rinsed and drained
1 cup chopped walnuts
1 tablespoon vanilla extract
1/4 cup prune puree (pitted prunes blended with a little water)
1/4 cup instant coffee
1/4 teaspoon salt
4 eggs
3/4 cup honey or agave nectar

Preheat oven to 325. Butter and flour a 9-by-13-inch baking pan (this will make brownies about 1/2 inch thick; for thicker brownies use a 9-inch square pan).

Heat chocolate and butter in microwave 2 minutes on high; stir to melt.

Place beans, half the walnuts, vanilla, prune puree and two spoonfuls of chocolate mixture in food processor and blend 2 minutes, until smooth.

In large bowl, mix remaining walnuts, coffee, salt and remaining chocolate mixture. Add bean mixture and stir well.

In separate bowl, beat eggs until light and creamy, about 1 minute. Add honey or agave nectar and beat well. Reserve 1/2 cup of this mixture; pour the rest into the batter and mix well.

Pour batter into pan and smooth top.

Beat remaining egg mixture until light and fluffy. Drizzle over brownie batter, and use a toothpick to pull it through the batter for a marbled effect. Bake 30 to 40 minutes, until set. Cool, then refrigerate several hours before cutting. Makes about 24 2-inch brownies.

Chocolate Chip Cookies

2-1/2 cups “;white”; whole wheat flour (or 1-1/2 cups whole wheat flour and 1 cup unbleached white flour)

1-1/2 cups brown sugar

1-1/2 teaspoon baking soda

1/2 cup prune puree

1/2 cup (1 stick) butter, softened

1/4 cup honey

2 teaspoons vanilla

2 eggs

1 cup chocolate chips

1 cup chopped walnuts (optional)

Preheat oven to 350 degrees.

Sift flour, sugar and baking soda together.

Combine prune puree, butter, honey, vanilla and eggs in another bowl. Combine with flour mixture. Stir in chocolate chips and nuts. Roll into golf-ball-size balls, place on cookie sheet and flatten. Bake 10 to 15 minutes. Makes about 24 2-1/2 inch cookies.