Some recipes stand the test of time—and this one is a true classic in my kitchen. I first discovered it as a teen, printed right on a jar of Hellmann’s mayo. Since then, it’s become my family’s all-time favorite chocolate cake. Over the years, my handwritten copy of the recipe has collected its fair share of smudges and cocoa fingerprints—a sure sign of how often I return to it.

What makes it special? Mayonnaise. It sounds strange at first, but don’t let that stop you. Mayo is made of eggs and oil, both of which are essential in cake baking. Instead of adding them separately, this recipe blends them into one secret ingredient that gives the cake an unbelievably moist and tender crumb. It’s easy to make, hard to mess up, and always a crowd-pleaser.