One of the easiest cakes you'll ever bake, this old-fashioned one bowl chocolate mayonnaise cake needs only 7 ingredients and no butter or eggs! It was a mid-century staple and this recipe comes from Alex's grandmother-in-law, who made it for decades. We promise, the cake doesn't taste like mayo.
This is a type of recipe that you'll find – with several different iterations – in community cookbooks across Canada from around the 1940s to the 1970s or so. It's a staple for Manitoba bakers but Kelly, on the East Coast, had never heard of it. Maybe your grandmother or an aunt made cake with mayonnaise!
Ingredient Notes and Substitutions
- Mayonnaise: the mayo provides the lift of eggs and the richness from oil, so you have no need for added fresh ingredients like milk, eggs, or butter. Make sure to use real mayonnaise and not a low-fat substitute as the results will be unpredictable.
- Cocoa: be sure to use natural cocoa and not Dutch process. This cake is leavened with baking soda, which won't react with Dutch process cocoa (it would make for a flat, dense cake).
- Flour: we haven't tried making this recipe with gluten-free flour and have only ever made the cake as written.
Use the JUMP TO RECIPE button at the top, or scroll to the bottom of the post to see the printable recipe card with full ingredient measurements and complete instructions.
Step 1: whisk the mayonnaise and water in a large mixing bowl.
Step 2: add all of the remaining ingredients but flour and mix to combine, then stir in the flour.
Step 3: spread into a lined square baking tin.
Step 4: bake for about 40 minutes and cool before frosting.
- Be sure to add the flour last: this makes for a perfectly mixed cake with little risk of over-mixing. If you add the flour with the other dry ingredients, you'll end up with a chewy cake that doesn't rise as much.
- Don't over-mix: also why the flour is added last. A few lumps in the mix are fine and you don't want to risk mixing too long to activate the gluten in the wheat flour.
- Don't use light mayonnaise: trying to use a low-fat, vegan, or (dread) mayo substitute will result in a denser, chewy, and all-around poor quality cake.
The mayonnaise replaces any need for additional eggs or fat, so you don't need to mix in any eggs (or worry about room temperature ingredients). Traditional mayo is made with eggs, acid – usually vinegar – and oil, so it's the ideal addition for a very easy light and fluffy chocolate cake. The vinegar reacts with the baking soda to add more lift.
Many other chocolate mayonnaise cake recipes available online use more standard modern methods and add eggs or buttermilk. It's just not necessary and makes a needlessly finicky cake, while this one is a perfect pantry recipe that's tried and true.
If you have a 9-inch square baking tin, the bake time will be about half an hour. In any case you can do a toothpick test to see if it's done.
How to Store
Storage: keep in a sealed container at room temperature for up to 3 days, and refrigerate for longer storage.
Freezing: transfer the fully cooled cake to an airtight container (it can be iced with the brown sugar frosting) and freeze for up to a month. Thaw at room temperature before serving.
What does mayonnaise do to cake?
Mayonnaise replaces the need for eggs or oil (or butter) in cake, adding lift and moisture.
Can I use hot cocoa mix?
No, the blend used to make hot cocoa or hot chocolate contains added sugar and sometimes other ingredients like milk powder. Subbing it for cocoa powder will make for a denser, less chocolate-y cake.
Can I substitute Miracle Whip for mayonnaise?
While they can usually be used interchangeably, Miracle Whip contains added water, less oil, and has added sugar. It will negatively alter the texture and taste of the cake.
If you make this Chocolate Mayonnaise Cake recipe or any other chocolate recipes on the Baked Collective, please take a moment to rate the recipe and leave a comment below. It’s such a help to others who want to try the recipe. For more baking, follow along on Instagram, TikTok, and YouTube.
Chocolate Mayonnaise Cake
- Measuring cups and spoons or a digital kitchen scale
- Mixing bowl
- 8-inch (20 cm) square baking tin
- 1 cup full-fat mayonnaise
- 1 cup water
- 1 cup white sugar
- ¼ cup cocoa powder
- 2 teaspoons baking soda
- ½ teaspoon salt
- 2 cups white flour
- Preheat the oven to 350°F (180°C) and grease or line an 8-inch (20 cm) square baking tin.
- Add the mayonnaise and water to a large mixing bowl and whisk to combine.1 cup full-fat mayonnaise, 1 cup water
- Whisk in the sugar, cocoa, baking soda, and salt until no lumps are visible. Mix in the flour until just combined, being careful not to overmix. Some lumps at this point are fine.1 cup white sugar, ¼ cup cocoa powder, 2 teaspoons baking soda, ½ teaspoon salt, 2 cups white flour
- Transfer the cake batter to the prepared tin and smooth out the top. Bake for 35-40 minutes, or until a toothpick inserted into the middle of the cake comes out clean.
- Cool fully before frosting and serving. This cake can be stored for up to 3 days at room temperature and freezes well.