How fine fat is! The same ingredient that makes dessert delicious goes straight to the pooch beneath my wannabe six-pack. I want to make my cake and eat it too, so I experiment with ways to make dessert healthier.

The oldest trick in low-fat baking is to replace half of the butter or oil with applesauce. Besides being moist, applesauce contains sugar, which tenderizes dough. Applesauce works beautifully in quick breads and spice cakes but not so well in pound cakes and pie crusts, where butter is crucial to the flavor or flakiness. Applesauce also doesn’t fare as well in cookies. It contains too much moisture, so cookies get cakey, and you lose the crisp edges.

There are a couple ways to get around the applesauce conundrum. For cookies, you can omit up to half the butter because they’re so rich already. I usually leave out 1/3 or 1/4 just to be safe. Or, you can use a different fat substitute to mimic the texture you want.

Other cultures have long known that pureed beans are sumptuously smooth. Good Israeli hummus, for example, is as rich as butter. I’d take The Hummus Place’s signature dish over foie gras any day. The Chinese and Japanese add sugar to pureed beans, nestling it inside pastries.

As seen in the black-eyed susan cake, pureed beans are actually a pretty good fat substitute. If you don’t believe me, scientific experiments have shown that pureed white beans can replace up to half the fat (by weight) in cookies and brownies. To take advantage of the beans’ smooth texture, I used them in a fudgy brownie recipe.

Brownies come in several varieties: fudgy, cakey and chewy. I generally prefer them chewy, because they most closely resemble the boxed mixes I grew up on. Alice Medrich has a divine, low-fat, chewy brownie recipe in Chocolate and the Art of Low-Fat Desserts and Cookies and Brownies. Chewy brownies use cocoa powder, which has great flavor, but they’re missing cocoa butter: that magical ingredient that melts in your mouth.

If I’m feeling decadent, I switch my loyalty to fudgy brownies, which are chocolate in “cake” form. Purists insist that real brownies have no baking powder or soda, just plenty of chocolate, eggs for leavening, and enough flour to hold it all together.

My favorite fudgy recipe has a whopping 12 ounces of chocolate, three sticks of butter, three cups of sugar, six eggs and just over a cup of flour. If there ever was a poster child to use bean puree as a fat substitute, this was it. In this adapted recipe from The Farm of Beverly Hills, melt the chocolate and one and a half sticks of butter over a double boiler. Then, whisk in six ounces of white bean puree and the eggs. Add the cake flour, cocoa powder, sugar and salt and bake. The recipe says it yields 20 brownies, but I got 36 small but very rich brownies.

The end result was very moist, smooth and delicate. It was so delicate, in fact, that you could probably get away with using all-purpose flour. They did not taste beany or like they were reduced fat. I noticed less buttery flavor, but only because I had eaten the regular brownies before. Anyone else would not be able to detect the secret ingredient.

How to Make White Bean Puree:

If starting from scratch, soak dry cannellini, great northern, or white kidney beans with water by at least two inches. Cover and let stand for up to 24 hours; refrigerate if the kitchen is very warm. Soaking is optional, but it can save anywhere from 30 minutes to an hour of cooking time. To cook the beans, drain them and cover with water to cover by two inches. Bring to a boil over high heat. Skim off the foam that rises to the surface. Reduce heat to low and simmer, covered, stirring occasionally until they are very soft. Unsoaked cannellinis take about 30 minutes; great northerns and white kidney beans take one to 1 1/2 hours. Dry beans will swell to about three times their original size.

Measure out six ounces, or about 1 1/3 cup of cooked beans. If you are using canned beans, rinse them thoroughly to get rid of excess salt. Puree in a blender or food processor until smooth. You should have 3/4 cup of puree.

Notes/tips:

• The salt is very important in this recipe to give off that buttery flavor.
• Whisk the eggs in just to combine. Do not beat them, as the extra air will make the brownies cakey (which is fine if you like cakey brownies, but there are lower calorie recipes for that!).
• To make one cup of cake flour, subtract 2 Tbsp from one cup of all-purpose flour. Then add 2 Tbsp of cornstarch. Some say that cornstarch makes baked goods taste chalky, but I can’t detect it in such small quanities. If you despise cornstarch, just subtract the 2 Tbsp of all-purpose flour and don’t add anything else. In this recipe, you can get away with not doing any substitutions, if you like.
• To set the crust and leave the interior creamy, Alice Medrich developed the “Steve ritual.” After baking the brownies, immediately dunk the pan in an ice bath. Do not attempt with a glass pan; the sudden drop it in temperature will cause it to crack.
• These brownies will only be as good as the chocolate you use. Save your chocolate chips for cookies, and do not under any circumstances use Hershey’s. I’m not saying you have to go all out with Valrhona, but I used a mid-range chocolate from Jacques Torres.
• Silicone pans are stick resistant but not non-stick. Be sure to grease them.