This chocolate mayonnaise cake is an old-fashioned 9×13 sheet cake with a soft, tender crumb and a thick layer of chocolate buttercream on top. The mayonnaise is doing the work of the oil and the eggs, and you can’t taste it once the cake is baked.
It mixes by hand in one bowl, bakes in about half an hour, and travels to a potluck right in the pan. If you’ve been curious about mayonnaise cake but never quite talked yourself into it, this is the one to start with.
If this is your kind of cake, you’ll probably love my chocolate depression cake too. Same pantry-cake idea, just oil instead of mayonnaise and a little lighter. Coca-Cola cake is the other sheet cake my family asks for by name, and the rest of them live with my old-fashioned cake recipes.
Why Put Mayonnaise in Chocolate Cake?
Mayonnaise is oil and eggs already whisked together. That’s most of what you’d be adding to a chocolate cake anyway, so using it means you skip cracking eggs and measuring oil and get both in one scoop.
Because the fat is already emulsified, it spreads through the batter more evenly than loose oil does. That’s what gives this cake its soft, almost velvety crumb. No tang, no mayonnaise flavor, just chocolate.
Ingredient Notes
See the recipe card below for the full ingredient amounts and instructions.
- Mayonnaise. Use full-fat regular mayonnaise like Hellmann’s, Best Foods, or Duke’s. Skip Miracle Whip, and skip light or reduced-fat mayo.
- Cocoa powder. Regular unsweetened cocoa is all you need. You’ll whisk it into boiling water first, which does more for the chocolate flavor than any other step in this recipe.
- Brown sugar. Half the sugar is light brown sugar. It holds moisture, so the cake still eats soft on day two.
- Boiling water. It needs to be hot enough to bloom the cocoa, then cooled for 10 minutes before the mayonnaise goes in.
- Heavy cream. For the frosting. Milk works in a pinch, but the buttercream won’t be as silky.
You’ll also need all-purpose flour, granulated sugar, baking soda, baking powder, salt, and vanilla, plus butter and powdered sugar for the frosting. Keep a little extra cocoa powder handy for dusting the pan.
How to Make Mayonnaise Cake
Heat the oven to 350°F, or 325°F if you’re baking in a dark or nonstick pan. Grease a 9×13-inch pan and dust it with cocoa powder instead of flour so you don’t end up with white streaks on a chocolate cake.
1. Bloom the Cocoa
Whisk the cocoa powder into the boiling water until it’s completely smooth, then whisk in both sugars while the liquid is still hot so they dissolve all the way. Let it sit for 10 minutes. This step is doing two jobs. It wakes up the cocoa so the cake tastes richer, and it brings the temperature down enough that the liquid won’t break down the mayonnaise in the next step.
2. Whisk In the Mayonnaise
Whisk the mayonnaise and vanilla into the cooled cocoa mixture until smooth. It should look like thin chocolate pudding.
3. Add the Dry Ingredients and Bake
Whisk the flour, baking soda, baking powder, and salt together in a separate bowl, then add them to the wet mixture in two or three additions. Whisk until the batter is smooth with no pockets of dry flour. The batter will be thin and pourable, and that’s exactly right. Pour it into the pan and get it into the oven right away.
Bake 28 to 33 minutes, and start checking at 28. When the edges just begin to pull away from the sides of the pan, that’s your cue to start testing the center. The cake is done when the center springs back to a light touch and a toothpick comes out with a few moist crumbs clinging to it. A toothpick that comes out completely clean means it baked a little too long. Cool the cake completely in the pan before frosting.
Make the Chocolate Buttercream
Beat the softened butter until creamy, then beat in the cocoa powder. Add the powdered sugar gradually, alternating with the heavy cream, and finish with the vanilla and a pinch of salt.
Beat it on medium-high for two or three minutes at the end. That’s what turns it smooth and spreadable instead of stiff. If it still feels thick, add another tablespoon of cream.
Make sure the cake is completely cool before the frosting goes on. Buttercream on a warm cake tears the top and melts into the crumb.
Tips for a Moist Cake
- Don’t skip the cocoa bloom. Whisking the cocoa into boiling water is the biggest flavor step in the whole recipe.
- Whisk the batter smooth. Pockets of dry flour won’t work themselves out in a batter this thin, and you’ll see them in the baked cake.
- Watch the edges. When they just start pulling away from the sides of the pan, start testing the center. A toothpick that comes out clean means the cake is already past done.
- Use full-fat mayonnaise. Light mayo cuts the fat roughly in half, and you’ll taste the difference.
Make Ahead and Storage
You can bake and frost this cake a day ahead. Once it’s completely cool and frosted, cover it tightly and leave it at room temperature for up to 3 days.
Keep the covered cake in the refrigerator for up to 5 days. Let slices sit out for 20 to 30 minutes before serving so the crumb softens back up.
For longer storage, wrap the unfrosted cake or individual slices tightly and freeze for up to 3 months. Thaw overnight in the refrigerator or at room temperature.
Recipe FAQs
No. Once it bakes there’s no tang and no mayonnaise flavor at all. The mayonnaise is only there for the oil and eggs it’s already made from. What you taste is chocolate.
Almost always too much leavening in older mayonnaise cake recipes. They tend to call for 2 teaspoons of baking soda, which makes the batter rise fast and then collapse once the structure can’t hold it. The fallen part compresses into a dense, gummy layer, which is why a sunken cake can taste underbaked even when it isn’t. This recipe uses ¾ teaspoon of baking soda with 1 teaspoon of baking powder, which gives a good rise without the crash. Opening the oven door or bumping the pan before the center sets will also do it, so leave it alone until at least 28 minutes.
Full-fat mayonnaise works best here. Miracle Whip has added sugar and spices that change the flavor, and it’s lower in fat, so the cake won’t be as moist.
Yes. Divide the batter between two greased 9-inch round pans and bake 25 to 30 minutes, checking at 25.
Sure but it’s full of chocolate flavor as is. Fold in 1 cup of semisweet chocolate chips before pouring the batter into the pan.
More Cakes to Try
For another 9×13 cake with a different flavor, try this Strawberry Texas Sheet Cake. It starts with a cake mix and gets its strawberry flavor from Jell-O and preserves.
Or browse these old-fashioned desserts for more cakes, cobblers, and other familiar sweets.
Recipe
Chocolate Mayonnaise Cake
Equipment
- 1 9×13-inch baking pan
- mixing bowls
- Whisk
- electric mixer
- rubber spatula
- Measuring cups and spoons
Ingredients
Cake
- ½ cup unsweetened cocoa powder
- 1 ¼ cups boiling water
- 2 cups all-purpose flour
- ¾ teaspoon baking soda
- 1 teaspoon baking powder
- ¾ teaspoon fine salt
- 1 cup full-fat mayonnaise
- 1 cup granulated sugar
- ½ cup light brown sugar packed
- 2 teaspoons vanilla extract
- 1 tablespoon unsweetened cocoa powder for dusting the pan
Chocolate Frosting
- ½ cup unsalted butter softened
- ⅓ cup unsweetened cocoa powder
- 3 cups powdered sugar
- ½ cup heavy cream plus 1-2 tablespoons more if needed
- 1 teaspoon vanilla extract
- 1 pinch salt
Instructions
Cake
- Heat the oven to 350°F, or 325°F if you’re using a dark or nonstick pan. Grease a 9×13-inch pan and dust it with cocoa powder instead of flour so you don’t end up with white streaks on a chocolate cake.
- Whisk the cocoa powder into the boiling water until completely smooth, then whisk in the granulated sugar and brown sugar while the liquid is still hot so they dissolve all the way. Let it sit for 10 minutes to cool to warm. This wakes up the cocoa so the cake tastes richer, and it brings the temperature down enough that the liquid won’t break down the mayonnaise.
- In a separate bowl, whisk together the flour, baking soda, baking powder, and salt until there are no clumps.
- Whisk the mayonnaise and vanilla into the cooled cocoa mixture until smooth.
- Add the dry ingredients to the wet in two or three additions, whisking until the batter is completely smooth with no streaks or pockets of dry flour. The batter will be thin and pourable, and that’s exactly right.
- Pour the batter into the prepared pan and get it into the oven right away.
- Bake 28 to 33 minutes, checking at 28. When the edges just begin to pull away from the sides of the pan, start testing the center. The cake is done when the center springs back to a light touch and a toothpick comes out with a few moist crumbs clinging to it. If the toothpick comes out completely clean, it baked a little too long.
- Set the pan on a wire rack and cool the cake completely before frosting.
Chocolate Frosting
- Beat the butter until creamy, then beat in the cocoa powder until fully incorporated.
- Add the powdered sugar gradually, alternating with the heavy cream. Beat in the vanilla and salt.
- Beat on medium-high for 2 to 3 minutes until smooth, glossy, and spreadable. Add another tablespoon of cream if it’s stiff.
- Spread evenly over the cooled cake.
Notes
Nutrition
Nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content will vary with brands used, measuring methods, portion sizes and more.
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