First, make sure you did not over-bake your brownies. Cooking them too long will make them dry out and become more cake-like. Beyond that, the secret lies with the recipe. A great fudgy brownie recipe will contain a high percentage of fat in the form of butter, and an egg for the custard-like center it creates. It also will not contain much flour--just enough to barely hold it together. If you’re using my recipe for brownies, you will always have fudge-like results.