Mayonnaise cake is popular because it’s delicious, but it’s also popular because it’s simple. The mayonnaise acts as the fat supplement in the cake, meaning that you can make a perfectly wonderful chocolate cake with just flour, sugar, cocoa, and some mayonnaise.  The special ingredient eliminates the need for milk, butter, or even eggs! A simple water and mayonnaise will do the trick. This is helpful for a few reasons. If you don’t have access to or can’t keep normal perishable ingredients (such as milk and eggs), mayonnaise is a long-term substitute. For example, during 2020 when the grocery stores were empty, I made my boyfriend this cake for his birthday because it is made entirely with non-perishable ingredients (just like these 6 Recipes You Can Make with Non-Perishable Ingredients). It’s beautifully versatile and resilient.