Well, you must have some form of chocolate if you're really going to make chocolate brownies. What do you have that you can substitute? Do you have unsweetened chocolate? Do you have chocolate chips?

For every 3 tablespoons of cocoa called for in your recipe, substitute 1 ounce of unsweetened chocolate, but cut out 1 tablespoon of fat from the recipe. Or substitute 2 ounces of semisweet chocolate but cut the fat by 1 tablespoon and the sugar by 3 tablespoons.

Some people might be willing to substitute 3 heaping tablespoons of carob powder for 3 tablespoons of cocoa (but some would not), and if you don't have cocoa powder, what is the likelihood that you have a cupboard full of carob?