Duff Goldman Wants You To Save Your Leftover Mashed Potatoes. Here's Why

After spending hours making a cake for a special occasion, it's heartbreaking when you finally cut that first slice and it crumbles into pieces. A dry, crumbly cake is often the result of common baking mistakes like overbaking or not using enough butter, oil, or other fats. If you have tried a ton of recipe upgrades to make your cake more moist and rich and still haven't found one that works for you, we have a trick you probably haven't ever heard of: using leftover mashed potatoes. According to executive chef and "Ace of Cakes" alum Duff Goldman, mashed potatoes could be the key to a firm, moist, and dense cake. 

In an interview with the Food Network, Duff says, "Root vegetables, especially potatoes and carrots, hold moisture really, really well," making them a great addition to a box cake mix or made-from-scratch cake that is in danger of being too dry. The best potatoes to use are Russet potatoes, as they are high in starch and can help the other ingredients in your cake bind together more effectively. This means your cake will have a better structure and a finer crumb. If your mashed potatoes don't contain dairy, they are also a great dairy-free substitute for other creamy secret cake ingredients like mayonnaise, sour cream, and yogurt. 

The key thing to remember when using mashed potatoes to make your cake moister and denser is that you don't want to go overboard. If you add too much mashed potatoes, your cake is in danger of being too starchy and gelatinous, or tasting like the dinner you had the night before instead of dessert. For most cake recipes, two or three tablespoons of mashed potatoes is plenty.

However, your success may depend on whether you are substituting other ingredients as well. If you are already trying out a bunch of other ingredients to elevate your boxed cake mix, you may end up with a dessert that is too soupy or has a strange texture. The overall results you get will depend on the chemistry between all of your ingredients. When you start substituting ingredients and changing ratios, there's a higher risk that some of them won't get along. If you aren't an experienced baker, try to use only one substitution per recipe until you learn more about how ingredients interact. While you can use mashed potatoes that are leftover from your meal the night before, it's better if the potatoes are unseasoned.