When it comes to baking, there are a number of ways to minimize the amount of fat in a recipe without settling for a final product that is heavy and dry. Chocolate cakes are ideal candidates for low-fat recipes because of the chocolate's naturally rich and robust flavor. Although substitutions can make cakes denser, there are techniques you can use to keep the cake soft and fluffy. Additionally, some classic cake recipes owe their light and springy qualities to whipped egg whites without the aid of added fats, so no substitutions are necessary.
Substitute an equal amount of plain yogurt. Thick yogurt such as Greek-style yogurt works best and does not compete with the taste of the chocolate.
Substitute mashed avocado. The creamy texture of avocado makes it a comparable substitute for butter in a 1 to 1 ratio. It will impart a mild avocado flavor, so consider using additional spices or using it as a substitute for just part of the butter to minimize its impact on the overall flavor of the cake.
Substitute unsweetened applesauce (or another fruit puree) in a 1 to 1 ratio. The apple flavor is usually noticeable but not overwhelming. Be aware that dense fruit purees such as prune puree will weigh down the cake more than applesauce will.
Make a chocolate angel food cake for a fluffy cake that is virtually fat-free. To flavor a standard angel food cake recipe, replace one-fourth of the flour with an equal amount of sifted unsweetened cocoa powder.
Make a classic chocolate sponge cake. Most sponge cake recipes contain little or no butter or oil and have a light and springy quality.
Use cake flour rather than all-purpose flour. Because cake flour is lower in protein, it will help prevent gluten from forming and toughening the cake. It also has a finer, softer consistency.
Use natural – not Dutch-processed – cocoa powder unless the recipe specifies otherwise. Natural cocoa powder is acidic and will react with the baking soda in the batter to create a lighter cake.
Sift the dry ingredients to aerate them. Use a whisk to stir them together.
Follow proper mixing techniques. Most cakes rely on the formation of air bubbles to achieve a light crumb texture. To preserve the air bubbles, use a spatula to gently fold in the dry ingredients after you have beaten the sugar with the butter or oil substitute and the eggs.
Don't over-bake. The cake is done when it springs back from a gentle poke. After the cake is fully cooked it will start to shrink and dry out, becoming denser.