I'm making a scratch
spice cake for my son's wedding. Will brown sugar make the cake more moist, instead of white sugar?
yes a bit
but these ingredients are not always interchangeable either -- i have a brownie recipe that when i switch to b sugar i can make individual 'crater brownies' that have a big hole in there and it's a wonderful lush texture and you can fill the crater with a scoop of ice cream or whipped cream or whatever --
but for cake just depends on what you're doing it might be fine it might not
Sugar is hydroscopic, it attracts water from the environment. Part of the role sugar place in baking is to attract water from the flour thereby preventing too much gluten from developing. Substituting with brown sugar will produce a moister cake, but be aware of all the liquids in your recipe since it holds more moisture than white sugar. You don't want to undermine the cake's structure.