Chocolate mayonnaise cake may sound a little strange, but when you think about it, most mayo recipes (or store bought) contains oil and eggs, which are typically used in a packet mix for a cake – ‘just add eggs and oil’ etc…. so that’s why this recipe has on the official list no eggs or butter, but instead you end up with a lovely super light, creamy and moist sponge which is very addictive indeed! To take things up a notch for freshness we make our own homemade mayonnaise too, this is optional, but I think doing it really helped me understand the recipe more and may have made it that little bit more creamy. Good luck if you try it, it’s actually really nice!
How to make a chocolate mayo cake from scratch
Lets make the mayo first and put it in the fridge to chill. Mix the egg yolks and mustard together with a whisk in a bowl with the salt, slowly add the oil in very small batches whisking as you go until the oil is all incorporated, do not rush this step, keep whisking as you see the texture change. Add the lemon juice and whisk through until thickened, keep in the fridge and weigh out 225g for the sponge when you need it.
For the sponge add the mayo, flour, sugar and baking powder together and whisk well, it will turn to a dry like pastry texture. Add in the water, cocoa and vanilla extract and whisk really well until smooth. Pour into 2 lined cakes tins evenly and bake in a pre-heated oven at 160fan or equivalent for 30 minutes. Check with a bamboo skewer that it is ready if it comes out clean, if not, keep baking and check every 5 minutes. Allow to cool fully in the tin whilst you make the buttercream.
For the buttercream use an electric whisk and beat together the butter and icing sugar until softened and creamy. Add the cocoa powder and milk and keep whisking until smooth, if it’s still a bit stiff add some more milk, but only very small amounts at a time.
Wedge the 2 cake sponges (that are quite delicate so handle with care) with the buttercream and slice up, super moist, creamy and very, very addictive… so much so I’m off to eat a slice now after typing this out! Enjoy and good luck.