What can I substitute for oil in brownies and still get fudgy brownies? I've tried yogurt and sour cream (individually) and only replacing half the oil with one of those, but the brownies always end up cakey. Should I just give up and accept that brownies are not a health food, or are there other ways to use less oil?
If you have a recipe that already produces a dense fudgy brownie and you're looking to do it without oil, you're just out of luck.
If you're looking to produce a dense fudgy brownie and wondered if, while you were at it, you might cut back on the oil...NO, but here are some suggestions for making a cakey brownie more dense and "fudgey":
Follow Tim's advice above on using butter instead of oil. It's not doing anything as far as calories but it will produce better flavor vs. a neutral oil. However, particularly if you're planning to put nuts in them, you could replace a portion of the vegetable oil with walnut or hazelnut oil for enhanced nutty flavor.
Replace half of the whole eggs with egg yolks. Cakiness in brownies is partly due to the use of whole eggs. Egg whites have a drying effect on baked goods. In converting a brownie recipe I did, I used 2 egg yolks for each whole egg.
Replace part of the granulated sugar with corn syrup. They hygroscopic nature(ability to absorb moisture and retain it) of the corn syrup will create a more dense moist result. I think I replaced about half the sugar with corn syrup. The added moisture of the corn syrup will help to off-set the loss of moisture from removing the egg whites.
Heat chocolate, butter, cocoa powder over a hot water bath until chocolate is melted. Stir to blend to a smooth consistency. Set aside to cool slightly.
Beat egg yolks/whole egg with sugar and corn syrup until thick, light in color, and mixture forms a "ribbon".
Combine dry ingredients and make a well in the center.
Temper chocolate into egg/sugar mixture. Mix to blend well. Add to dry ingredients and fold together just until moistened. Pour into greased pan and bake until set.
I make brownies by melting 250g of butter and 200g of couverture chocolate together in a saucepan over low heat. I think this is what makes them very moist and "fudgey."
I agree with the others who have commented - brownies are not a health food. Even if you could substitute the butter for oil to get the texture you desired, they still contain too much chocolate and sugar to be classified as a health food.