Chocolate Mayonnaise Cake — My Mom’s Old-Fashioned Birthday Cake

Why Mayonnaise in a Cake?

I get it. The first time somebody tells you there’s mayonnaise in a chocolate cake, you make a face. My husband certainly did.

But think about what mayonnaise actually is — it’s oil and eggs, whipped together. That’s it. And what does a chocolate cake batter need? Oil for the fat, and eggs for structure and richness. So when you stir a cup of mayonnaise into the bowl, you’re not adding something strange. You’re adding the exact same things you were already adding, just already emulsified and ready to go. That’s the whole secret, and it’s the reason this cake comes out so much more tender than a lot of scratch chocolate cakes do.

We still use three eggs in this recipe on top of the mayonnaise. The mayonnaise isn’t replacing them entirely — it’s carrying the fat and adding a little extra egg along with it.

And no, we don’t put mayonnaise in the icing. Somebody asked.

The Cake I Picked Every Year

My mom made this cake for me almost every year for my birthday. Out of everything she could have made, this is what I picked, year after year.

She almost always did it as a layer cake, which is why I made it that way here instead of in a 9×13. And she topped it with a cooked chocolate icing — the kind you boil on the stove for a minute and then whisk powdered sugar into. It comes out thin and glossy and it soaks into the top of the cake just slightly. It isn’t a thick buttercream, and I love that about it. The layer stays light, it’s not overly sweet, and it lets the cake itself be the star.

I hadn’t made this in years before we filmed it. I rarely make it just for myself these days. But the second I cut into it, all of it came back — every birthday, that same cake sitting on the table. I hope it’ll do something like that for your family too.

Chocolate Mayonnaise Cake

Prep Time: 20 minutes Cook Time: 30 minutes Cooling & Icing: 40 minutes Total Time: About 1 hour 30 minutes Servings: 12 Yield: One two-layer 9-inch cake

Ingredients

For the cake:

• 2 cups all-purpose flour
• 1 1/4 teaspoons baking soda
• 1/4 teaspoon baking powder
• 2/3 cup unsweetened cocoa powder
• 1 2/3 cups granulated sugar
• 1 teaspoon vanilla extract
• 3 large eggs
• 1 cup mayonnaise
• 1 1/3 cups water

For the old-fashioned chocolate icing:

• 1 stick butter (1/2 cup)
• 1/2 cup unsweetened cocoa powder
• 1/2 cup milk
• 2 cups powdered sugar
• 1 pinch salt
• 1 teaspoon vanilla extract

Instructions

1. Preheat your oven to 350°F and get your pans ready. Grease two 9-inch cake pans. You can flour them if you like, but with a chocolate cake I’d rather use cocoa — sprinkle a little in, shake it all around the bottom and up the sides, and tilt it over the second pan so the excess falls right in there instead of on your counter. A little parchment underneath catches the rest and you can pour it straight back into your cocoa.
2. Whisk your dry ingredients together. In a bowl, combine the flour, baking soda, baking powder, and cocoa powder. Use the dip-level-pour method for your flour so it isn’t packed too tight in the cup. Whisking helps break up any lumps in the flour and cocoa, so give it a good going over.
3. Beat the sugar, vanilla, and eggs. In your mixer bowl, add the sugar and vanilla, then the eggs one at a time — that way you can be sure every egg is a good one before it goes in. Mix for a minute or two, then turn it up to high speed and let it go a full three minutes. It’ll look completely different when it’s done: pale and fluffy.
4. Add the mayonnaise. One cup, leveled off. Turn the mixer to low and blend just until it’s incorporated — it doesn’t take long at all.
5. Alternate the dry ingredients and the water. Start with about a third of your flour mixture and mix on low until it’s almost combined, then add about a third of the water. Keep going that way — flour, water, flour, water — finishing with the flour mixture. Keep the mixer on low the whole time. You don’t want to over-beat this batter, so stop as soon as it comes together. Scrape down any flour hiding around the top edge of the bowl and mix just long enough to work it in.
6. Divide and bake. Pour the batter evenly between your two prepared pans and give them a little shake to settle out the bubbles. Bake at 350°F for about 30 minutes. Start checking at 28 — mine came out at 29 minutes. A toothpick in the center should come out clean. Your oven might be a little different, so watch it rather than the clock.
7. Cool the layers. Let them sit in the pans for 10 minutes, then turn them out onto cooling racks. If they stick a little, run a knife around the edge to loosen them. Let them cool all the way before you ice them.
8. Start the icing on the stove. In a saucepan over medium heat, combine the butter, cocoa powder, and milk. Whisk the cocoa into the milk as the butter melts. Once it comes to a boil, set a timer and let it boil for exactly one minute, stirring the whole time.
9. Finish the icing. Take it off the heat and whisk in the powdered sugar, the pinch of salt, and the vanilla. The salt is just there to cut the sweetness. If you want it perfectly smooth you can sift the powdered sugar first, but if you whisk well a couple of tiny lumps won’t hurt anything.
10. Let the icing set up — this part matters. Right off the stove it’s very pourable. If you baked this in a 9×13, that’s perfect: pour it straight over the warm cake and you’re done. For a layer cake you need it to thicken first. Give it about 12 to 15 minutes. Don’t walk off and forget it, though — it keeps hardening as it cools and you want to catch it at the right moment.
11. Ice and stack. Pour the icing carefully over the first layer, letting it come just to the edge. Set the second layer on top — I like to put mine on upside down so I’ve got a nice flat surface — and pour again, slowly. Let it sit a few minutes and it’ll set up faster now that it’s in a thin layer. Then come back with the rest of the icing, top it again, and glaze down the sides with a spreader if you’d like.
12. Slice and enjoy. This is a sticky, runny icing and I’ll be honest with you about that. If you’d rather it set up firmer, whisk in an extra cup of powdered sugar. I like it less sweet with this cake, so I leave it as it is.

Frequently Asked Questions

Can you taste the mayonnaise? No. Not even a little. It disappears completely into the chocolate — you’re tasting a rich, tender chocolate cake and nothing else. This is the number one thing people ask, and it’s the number one thing that surprises them.

What kind of mayonnaise should I use? Use real, full-fat mayonnaise. Whatever brand you normally buy is fine. Don’t substitute a salad dressing-style spread or a light or fat-free version — the fat is doing actual work in this recipe, and those products behave differently.

Why does mayonnaise work in a chocolate cake? Because mayonnaise is oil and eggs, which is what a chocolate cake batter already calls for. It’s not an odd addition; it’s the same ingredients in a different form, already emulsified. That’s what gives you such a tender, moist crumb.

Can I make this in a 9×13 pan instead of layers? Absolutely. The batter works either way. The 9×13 is actually easier when it comes to the icing — you can pour it right over the cake while it’s still warm and skip the waiting and stacking altogether.

Is there mayonnaise in the icing too? No. The icing is a traditional cooked chocolate icing with butter, cocoa, milk, powdered sugar, salt, and vanilla. The mayonnaise stays in the cake.

My icing is too runny. What do I do? It’s meant to be on the thin side, but if it’s more than you want, whisk in an extra cup of powdered sugar and it’ll set up firmer. You can also just give it more cooling time — it thickens noticeably as it sits.

Can I use a different icing? Of course. A simple chocolate buttercream is lovely on this cake. I use the cooked icing because it’s what my mom always put on it, and because the thin layer keeps the cake from getting too sweet. Use whatever you like best.

How should I store it? Keep it covered at room temperature for up to three days. The cake stays remarkably moist thanks to the mayonnaise, so it holds up better than most chocolate cakes on day two and three.

Can I freeze it? Yes. Freeze the unfrosted layers well wrapped for up to three months. Thaw them at room temperature and ice them the day you plan to serve it.