Your chocolate cake will be much moister if you replace the eggs and oil with this totally unexpected ingredient
No need to forgo a chocolate cake when you're short on eggs and oil: a jar from the fridge can save the day. This ingredient also changes the texture, making the crumb surprisingly soft.
When a craving for chocolate cake strikes and the egg carton or oil bottle is nearly empty, a jar from the fridge can save the day. This unexpected ingredient is mayonnaise: in the batter, it replaces both eggs and oil while giving a surprisingly moist texture.
This trick doesn't turn the recipe into an egg-free dessert, since the condiment already contains eggs, but it simply changes how they're incorporated. Mayonnaise adds fat and moisture in a single spoonful, provided you choose a classic, neutral-tasting product. This is where the success of the cake—and the surprise when you taste it—lies.
Why does mayonnaise make chocolate cake so moist?
Classic mayonnaise is a stable emulsion where the oil and water phases blend thoroughly, exactly what cake batter needs to remain pliable. The fat coats the flour particles, limiting gluten formation and preventing an elastic crumb. The American baking institute King Arthur Baking summarizes this idea by explaining that "the fat coats the flour and limits gluten development, which promotes a tender crumb." A chocolate mayonnaise cake is therefore based on this principle: incorporating eggs and oil, already emulsified, all at once.
Choosing the right mayonnaise and key quantities
To ensure the cocoa flavor remains prominent, the mayonnaise you choose should be plain, not low-fat, with a mild taste and no garlic, herbs, or chili. A mustard-flavored or flavored version would overpower the chocolate. This base is suitable for a square pan approximately 20 cm on each side, serving eight, and is made with the following proportions:
- 170g of classic plain mayonnaise
- 170 ml of lukewarm water
- 180 g of wheat flour
- 150 g of caster sugar
- 32g of unsweetened cocoa powder
- 1 teaspoon of vanilla extract
- 1 level teaspoon of baking soda, plus 1/4 teaspoon
- 1/4 teaspoon of fine salt
Preparation, cooking and serving for a successful soft cake
The oven is preheated to 175°C (350°F) using the conventional setting, while the baking pan is lined with parchment paper. The mayonnaise is whisked with the warm water and vanilla, then the sifted flour, cocoa powder, and baking soda are added to the bowl along with the sugar and salt. The batter is mixed just until smooth, without trying to make it foamy, before being poured and smoothed into the pan.
Baking takes approximately 30 minutes, with a check as soon as the top appears set: a thin knife inserted into the center should come out clean or with a few moist crumbs, without any trace of liquid batter. The cake then cools in its pan, placed on a wire rack to maintain a soft crumb. A first taste on its own allows you to judge the texture, then a dusting of powdered sugar, a few raspberries, or chocolate shavings complete the dessert, which should be kept covered to prevent drying out.
