This Strange Ingredient Makes Cakes Super Moist

Most home bakers have experienced the disappointment of slicing into a cake only to find it dry and crumbly. After all that effort mixing batter and waiting for it to bake, a dry cake feels like a total letdown. But what if the secret to perfectly moist cake was sitting in your refrigerator right now, and it’s something most people would never think to add? Celebrity baker Duff Goldman swears by an ingredient that sounds weird at first but makes total sense once explained. This simple addition can transform any cake from mediocre to amazing, and it’s probably already in your kitchen.

Mayonnaise creates surprisingly moist cakes

When Duff Goldman revealed his secret ingredient during a live Q&A session, many viewers were shocked to hear him recommend adding mayonnaise to cake batter. It sounds absolutely bizarre to put a sandwich condiment into dessert. But before dismissing this idea completely, think about what mayo actually contains. The two main ingredients in mayonnaise are eggs and oil, which happen to be the same base ingredients used in almost every cake recipe. The difference is that mayo has these ingredients already emulsified together into a creamy mixture.

This emulsification is what makes the magic happen in your cake batter. The blended texture helps create a creamier batter that bakes into an incredibly moist cake with a tender crumb. For a standard recipe that makes two nine-inch round cake layers, Goldman recommends adding just two tablespoons of mayo. That small amount won’t make your cake taste like a sandwich or give it any weird flavor. Instead, it simply adds extra moisture and richness that keeps the cake soft for days after baking.

Leftover mashed potatoes work as a secret weapon

The second unusual ingredient Goldman swears by might sound even stranger than mayo. He actually recommends adding a few tablespoons of leftover mashed potatoes to cake batter. Yes, the same mashed potatoes that go with steak or chicken can make dessert better. This isn’t a new trick either. Bakers have been using this method for generations, particularly for chocolate cakes. The starch in potatoes helps retain moisture throughout the baking process and keeps cakes from drying out as they cool.

Root vegetables like potatoes and carrots hold water really well, which is exactly what creates a moist texture in baked goods. Adding mashed potatoes also makes the cake slightly more dense, which Goldman personally loves. The best part is that mashed potatoes don’t add any weird taste to the finished cake. The other ingredients mask any potato flavor completely. So next time there are leftover mashed potatoes from dinner, save a few spoonfuls in the fridge and use them in the next cake instead of throwing them away.

Use buttermilk instead of regular milk

Beyond weird ingredients, there are some standard swaps that professional bakers always make to improve moisture. Buttermilk is one of the best substitutions anyone can make in cake recipes. Many home bakers stick with regular milk because that’s what they have on hand, but buttermilk makes a noticeable difference. The slight acidity in buttermilk breaks down gluten strands in the batter, which creates a more tender crumb. Less gluten development means the cake stays softer and doesn’t get tough or chewy.

Buttermilk also adds a subtle tangy taste that balances out the sweetness in cake batter. This creates a more complex overall taste without being obvious. Some experienced bakers get skeptical when they see a cake recipe calling for regular milk instead of buttermilk. While swapping buttermilk into any recipe might require adjusting other ingredients like baking soda, it’s usually worth the effort. The texture improvement from using buttermilk is significant enough that many professional bakeries won’t even consider using regular milk in their cakes.

Adding vegetable oil keeps cakes soft

Butter creates wonderful taste in cakes, but it’s not the best option for moisture. Once butter cools down, it solidifies. That’s why cakes made entirely with butter can feel a bit firmer when stored in the refrigerator. Vegetable oil stays liquid even when cold, which means cakes made with oil maintain a soft, tender texture at any temperature. Pulling a slice of cake straight from the fridge and having it still feel moist and soft is the goal.

The solution isn’t to completely eliminate butter, since it adds such good taste. Instead, professional bakers often use a combination of both butter and vegetable oil. This gives the best of both worlds: rich butter taste plus the lasting moisture that oil provides. Many bakery recipes use this method to create cakes that taste amazing and stay moist for several days. When baking at home, try replacing about half the butter in a recipe with an equal amount of vegetable oil to see the difference it makes.

Instant pudding mix adds moisture retention

Another trick used in professional bakeries involves adding instant pudding mix or a product called Instant Clearjel to cake batter. Instant Clearjel is basically modified cornstarch that helps baked goods retain more moisture. Most home bakers have never heard of it since it’s not commonly sold in regular grocery stores. The good news is that instant pudding mix contains Instant Clearjel as the second ingredient, making it an easy substitute that’s available everywhere.

Adding a small amount of instant pudding mix to cake batter helps the finished cake hold onto moisture better. This means the cake stays soft and fresh-tasting for more days after baking. The pudding mix can also add a little extra sweetness and sometimes a complementary taste depending on which type is used. Vanilla pudding mix works great in vanilla or white cakes, while chocolate pudding mix enhances chocolate cakes. Just a few tablespoons mixed into the batter can make a significant difference in the final texture.

Lower oven temperature prevents drying out

Even with perfect ingredients, baking technique matters just as much for creating moist cakes. One common mistake is baking at too high a temperature. Many home ovens run hotter than the temperature shown on the dial, which leads to overbaked, dried-out cakes. Professional bakers often bake cakes at lower temperatures like 300 or 325 degrees instead of the standard 350 degrees. The lower heat allows cakes to bake more evenly without the outside getting overdone before the inside finishes cooking.

Investing in a simple oven thermometer is one of the best ways to improve baking results. These inexpensive tools show the actual temperature inside the oven, which often differs from what the dial indicates. Many home bakers discover their oven runs 25 degrees hotter or cooler than expected. Once this is known, adjustments can be made to get the correct baking temperature every time. Always place cake pans on the middle or upper rack to avoid the direct heat from the bottom heating element, which can make the bottom of cakes too brown and dry.

Check cakes earlier than recipe suggests

Recipe times are just estimates since every oven bakes differently. Waiting until the end of the suggested baking time to check a cake often results in overbaking. Professional bakers start checking their cakes at least five minutes before the earliest time listed in a recipe. Then they continue checking every few minutes until the cake is perfectly done. A toothpick or thin knife inserted in the center should come out clean without wet batter, but checking too slowly can collect crumbs and give false results.

Another way to test doneness is by lightly pressing the top of the cake with a finger. If it springs back instead of leaving an indent, the cake is ready. Taking cakes out of the oven at exactly the right moment prevents that extra few minutes of baking that can dry everything out. Once a recipe has been made a few times, make a note of the exact baking time that worked best. But still check a bit early each time since factors like how many pans are in the oven can affect cooking time.

Simple syrup seals in moisture after baking

Professional bakeries have one final trick for keeping cakes moist that home bakers often skip. After the cake layers cool, they brush simple syrup over the top of each layer before frosting. Simple syrup is exactly what it sounds like: equal parts water and sugar heated until the sugar dissolves. This thin sweet liquid soaks into the cake surface and creates a barrier that seals in all the existing moisture. It won’t rescue a dry cake, but it will keep an already-moist cake from drying out over the next few days.

Making simple syrup takes just a few minutes in the microwave. Mix equal amounts of water and sugar in a microwave-safe bowl, then heat in short bursts while stirring until the sugar completely dissolves. Let it cool slightly, then use a silicone pastry brush to lightly coat the cake layers. Some bakers prefer making sweetened glazes instead, like lemon juice mixed with powdered sugar for lemon cakes, or cream of coconut for coconut cakes. These add both moisture and extra complementary taste at the same time.

Creating bakery-quality moist cakes at home doesn’t require expensive equipment or complicated techniques. Simple ingredient swaps like using buttermilk instead of milk, adding a combination of butter and oil, or incorporating unusual ingredients like mayo or mashed potatoes can transform results. Paying attention to baking temperature and timing prevents the overbaking that dries out so many home-baked cakes. With these professional secrets, anyone can make cakes that stay incredibly moist and delicious for days after baking.

Super Moist Chocolate Mayonnaise Cake

Course: DessertCuisine: American

Servings

12

servings

Prep time

15

minutes

Cooking time

30

minutes

Calories

385

kcal

This incredibly moist chocolate cake uses mayonnaise as a secret ingredient that creates the most tender, rich crumb that stays soft for days.

Ingredients

• 2 cups all-purpose flour

• 2 cups granulated sugar

• 3/4 cup unsweetened cocoa powder

• 2 teaspoons baking soda

• 1 teaspoon baking powder

• 1 teaspoon salt

• 1 cup buttermilk, at room temperature

• 1 cup hot coffee or hot water

• 1/2 cup mayonnaise

• 1/2 cup vegetable oil

• 2 large eggs

• 2 teaspoons vanilla extract

Directions

• Preheat the oven to 325 degrees F. Grease two 9-inch round cake pans with butter or cooking spray, then line the bottoms with parchment paper circles. Lightly grease the parchment paper as well to ensure easy cake removal after baking.
• In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt until well combined. Make sure there are no lumps in the cocoa powder by sifting it first if needed. Set this dry mixture aside while preparing the wet ingredients.
• In a separate bowl, whisk together the buttermilk, hot coffee, mayonnaise, vegetable oil, eggs, and vanilla extract until smooth and well blended. The mayonnaise should be fully incorporated into the mixture without any visible chunks remaining. The hot liquid will help the mayonnaise blend more easily.
• Pour the wet ingredients into the bowl with the dry ingredients. Stir gently with a wooden spoon or rubber spatula just until combined, being careful not to overmix. The batter will be quite thin and liquidy, which is exactly what creates the moist texture, so don’t worry if it seems runny.
• Divide the batter evenly between the two prepared cake pans. Use a kitchen scale if available to ensure equal amounts in each pan for even layers. Tap the pans gently on the counter a few times to release any air bubbles trapped in the batter.
• Bake for 28-32 minutes, checking for doneness starting at 28 minutes. The cakes are done when a toothpick inserted in the center comes out clean or with just a few moist crumbs. The top should spring back when lightly pressed with a finger.
• Remove the cakes from the oven and let them cool in the pans for 10 minutes. Run a knife around the edges to loosen, then invert onto a wire cooling rack. Peel off the parchment paper and let the cakes cool completely before frosting.
• Once cooled, brush the top of each cake layer with simple syrup if desired for extra moisture. Frost with your favorite chocolate buttercream or cream cheese frosting. Store the frosted cake covered at room temperature for up to 3 days or refrigerated for up to 5 days.

Notes

• Don’t skip the mayonnaise – it’s the secret to keeping this cake incredibly moist without adding any strange taste to the finished product.
• Using hot coffee instead of hot water intensifies the chocolate taste, but water works fine if preferred or for a kid-friendly version.
• The batter will be very thin and pourable, which is normal for this recipe and creates the signature moist texture.
• Make sure all ingredients are at room temperature before mixing for the best texture and even baking.
• This cake actually tastes better the next day after the moisture has distributed throughout, so feel free to bake it ahead.

Frequently asked questions

Q: Can you taste the mayonnaise in the finished cake?
A: Not at all. The mayonnaise completely disappears into the cake and doesn’t leave any flavor behind. It simply adds moisture and richness through the eggs and oil it contains. The chocolate and other ingredients completely mask any taste from the mayo, so even people who don’t like mayonnaise on sandwiches won’t detect it in the cake.

Q: What type of mayonnaise works best for baking?
A: Regular full-fat mayonnaise works best since the oil content is what creates moisture in the cake. Avoid using low-fat or light mayo because these products have less oil and more water or fillers that won’t provide the same results. Any brand of regular mayo will work fine, whether it’s Hellmann’s, Duke’s, or a store brand.

Q: How long will a cake made with mayonnaise stay fresh?
A: Cakes made with mayonnaise stay moist longer than traditional cakes, typically remaining fresh for 4-5 days at room temperature when properly covered. If refrigerated, they can last up to a week while maintaining their soft texture. The emulsified oils in the mayo help the cake retain moisture even after several days of storage.

Q: Can mashed potatoes be added to any cake recipe?
A: Mashed potatoes work best in chocolate cakes and spice cakes where their mild taste blends in easily. Start by adding 2-3 tablespoons of plain mashed potatoes (without added butter, milk, or seasonings) to a standard cake recipe. They add moisture and density but might change the texture too much in delicate white cakes or angel food cakes.