As long as you are okay with the slight change in taste and texture (typically sweeter and softer), you’ll have the best success substituting applesauce in oil-based baked goods, like quick breads, muffins and some cakes.
But let's get one thing straight: applesauce is not a great substitute for butter, and will lead to disaster in cookies and any other treat with a crispy snap. Unless you like cake-y, mushy cookies.
Most sources recommend a 1:1 swap: if the recipe calls for 1 cup of oil, substitute with 1 cup of applesauce. IMO, if you tinker too much from the start, you end up with Frankensnacks—a kind of scary and sad genetically modified version of a formerly good recipe.
So start easy. For a recipe that uses one cup of oil, use ½ cup of oil with ½ cup applesauce. If the finished product makes you happy, slightly increase the ratio of applesauce (2/3 applesauce: 1/3 oil; ¾ applesauce: ¼ oil) the next time to see how it affects the cake or muffin recipe. You may be able to do without oil completely, or you might find that as little as 1 or 2 tbsp. of oil added to the applesauce is ideal.
Interested in why this swap works (and when it doesn’t)? A short chemistry lesson: Although fats add richness and texture, the primary job of a fat in a recipe is to keep the flour protein from mixing with the moisture and forming long strands of gluten—a reaction that would give cake the texture of rubber tire. That’s why it’s so important to keep the liquid and dry ingredients separate until the very end, and to mix them together very gently by hand. When you substitute applesauce, it’s even more important to work the batter gently, and as little as possible, in the final mix. More tips for substitute success:
* Use unsweetened applesauce, or reduce the amount of sugar in the recipe if you use sweetened applesauce.
* Measure applesauce in a liquid measuring cup.
* Use a hand or stand mixer to thoroughly combine the applesauce with the other liquid ingredients (egg, flavoring), then blend the liquids with the sugar. With a large spatula, carefully fold the dry ingredients into the mixture until just combined.
* The finished product will be moist. Don’t alter the time for cooking because low-fat recipes dry out when they’re over-cooked.
Carrot Cake with Orange Cream Cheese Frosting (Okay, so the cream cheese frosting with heavy cream kinda defeats the low-fat angle. You can sub applesauce or another fruit puree for the olive oil and still cut loads of calories and fat—so the frosting won’t seem quite so over-the-top.)
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