Name: Chocolate Mayonnaise Sheet Cake Recipe
Prep time: 20 min
Cook time: 30 min
Total time: 1 h 20 min
Cuisine: American
Ingredients: Butter, for greasing the pan; 2 cups (242g) all-purpose flour; 1 cup (120g) unsweetened Dutch processed cocoa powder; 1 1/2 teaspoons baking powder; 1 1/2 teaspoons baking soda; 1/4 teaspoon salt; 3/4 cup (177ml) hot water; 2 tablespoons (30g) instant coffee powder or instant espresso powder; 2 large eggs; 1 cup (220g) sugar; 1/2 cup (100g) brown sugar, lightly packed; 1 cup (260g) mayonnaise; 1 tablespoon vanilla extract; 1/2 cup (80g) finely chopped semisweet or bittersweet chocolate; 1/2 cup (113g) unsalted butter; 2 tablespoons (30g) unsweetened Dutch processed cocoa powder; 1 cup (130g) powdered sugar; 1/2 cup heavy cream

There’s something irresistibly rich and tender about this Chocolate Mayonnaise Sheet Cake Recipe that I just can’t get enough of. It’s effortlessly moist, simple to whip up, and packed with deep chocolate flavor that always wins over everyone in my kitchen.

The image shows a clear glass baking pan with a thick, dark brown chocolate cake inside. The cake has a smooth, shiny layer of light brown chocolate frosting spread evenly on top. Three square pieces are cut from the cake and are lying next to the cake inside the pan, showing the dense, moist texture of the dark cake beneath the frosting. The background has a white marbled texture. photo taken with an iphone --ar 2:3 --v 7

Jump to:

Why You'll Love This Recipe
Ingredients & Why They Work
Make It Your Way
Step-by-Step: How I Make Chocolate Mayonnaise Sheet Cake Recipe
Top Tip
How to Serve Chocolate Mayonnaise Sheet Cake Recipe
Make Ahead and Storage
Frequently Asked Questions:
Final Thoughts
Chocolate Mayonnaise Sheet Cake Recipe

Why You'll Love This Recipe

This chocolate mayonnaise sheet cake has become a go-to for me whenever I want a dessert that’s both fuss-free and incredibly moist. The addition of mayonnaise might sound unusual at first, but trust me, it works wonders for keeping the cake unbelievably soft and tender.

Unmatched Moisture: Mayonnaise adds richness and moisture without making the cake greasy or heavy.
Effortless Preparation: You don’t even need a mixer for everything—this recipe is straightforward and forgiving.
Deep Chocolate Flavor: Using Dutch-process cocoa plus a touch of instant coffee enhances the chocolate notes beautifully.
Great for Any Occasion: The sheet pan format makes it perfect for parties, potlucks, or easy family desserts.

Ingredients & Why They Work

When making this Chocolate Mayonnaise Sheet Cake Recipe, every ingredient plays a part in creating that moist, tender, and flavorful result. Here’s a quick rundown of the must-have ingredients and some tips on making them work for you.

Flat lay of a small pat of fresh unsalted butter, a neat pile of all-purpose flour, a mound of rich unsweetened Dutch processed cocoa powder, a small heap of light brown sugar, a small heap of white granulated sugar, two large whole brown eggs with clean shells, a modest scoop of creamy mayonnaise, a small white bowl filled with hot dark coffee dissolved with instant espresso powder, a small white bowl of pure vanilla extract, a small white bowl of finely chopped bittersweet chocolate, a small white bowl of heavy cream, and a small white bowl of powdered sugar, all arranged in perfect symmetry on a clean white ceramic surface, placed on a clean white marble surface, soft natural light, photo taken with an iPhone, professional food photography style, fresh ingredients, white ceramic bowls, no bottles, no duplicates, no utensils, no packaging --ar 2:3 --v 7 --p m7354615311229779997

Butter: Used for greasing your pan to ensure the cake slips out easily without sticking.
All-purpose flour: The base that provides structure to the cake without weighing it down.
Dutch processed cocoa powder: This adds a rich, smooth chocolate flavor and a beautiful color to the cake.
Baking powder & baking soda: These leavening agents work together to give your cake the perfect lift and crumb texture.
Salt: Just a pinch to balance the sweetness and enhance all the chocolatey goodness.
Instant coffee powder or espresso powder: This is a game-changer for deepening the chocolate flavor without imparting a coffee taste.
Eggs: Bind everything and add richness to the cake’s texture.
White sugar and brown sugar: The combo of these two adds sweetness and subtle molasses notes that brown sugar offers.
Mayonnaise: Surprising, right? It keeps the cake superbly moist and soft, thanks to its oil and egg content.
Vanilla extract: Enhances all the flavors, adding warmth to the chocolate.
Finely chopped semisweet or bittersweet chocolate: For a luscious, glossy frosting with a real chocolate punch.
Unsalted butter: Provides creaminess and structure to the frosting.
Powdered sugar: Sweetens and smooths the frosting to the perfect consistency.
Heavy cream: Gives the frosting richness and helps create silky texture.

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Note: You'll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Make It Your Way

I love experimenting with this Chocolate Mayonnaise Sheet Cake Recipe by swapping up a few ingredients to make it truly mine. You’ll find it’s a great base to get creative with, whether you want it extra fudgy, a little lighter, or dairy-free.

Variation: Once, I swapped out the brown sugar for coconut sugar for a subtler caramel flavor and was pleasantly surprised at how well it complemented the cocoa.
Dietary modification: You can try using vegan mayonnaise to make a plant-based version—just check the egg replacement options to keep the texture right.
Flavor twist: Adding a teaspoon of cinnamon or a splash of chili powder to the batter brings a fun depth that’s unexpected but delicious.

Step-by-Step: How I Make Chocolate Mayonnaise Sheet Cake Recipe

The image shows a single square piece of dark chocolate cake with two layers on a white plate with a thin gold rim. The bottom layer is thick and dark brown with a moist, rich texture, while the top layer is a thick, smooth milk chocolate frosting with a slightly wavy surface. A golden fork rests on the plate next to the cake. In the background, two more pieces of cake on white plates with gold rims are slightly out of focus, all set on a white marbled textured surface. Photo taken with an iphone --ar 2:3 --v 7

Step 1: Prep Like a Pro

First things first—preheat your oven to 350°F (180°C) and butter your 9x13-inch pan thoroughly. This small step prevents a lot of heartbreak later by ensuring your cake doesn’t stick. While the oven warms, gather all your ingredients so they’re ready to go. Having everything at hand keeps the process smooth and stress-free.

Step 2: Mix Your Dry Ingredients

In a medium bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt. Stir them up until evenly blended. This helps make sure your cake bakes evenly and the leaveners don’t cluster in any one spot. I usually give it a few extra stirs just to be safe.

Step 3: Dissolve the Coffee

In a glass measuring cup, stir the instant coffee powder into the hot water until fully dissolved. This addition accentuates the chocolate flavor without tasting like coffee. I like this little trick because it makes the cake taste more intensely chocolaty and grown-up, without overpowering.

Step 4: Cream Mayonnaise & Sugars

Using an electric mixer, beat together the mayonnaise, white sugar, and brown sugar until the mixture is pale and creamy. It’s a bit different than creaming butter and sugar, but you’ll see the color lighten and the texture smooth out. This step sets the stage for a tender crumb.

Step 5: Add Eggs & Vanilla

Add eggs one at a time, beating after each addition until well incorporated. Don’t forget to scrape down the sides of your bowl occasionally—scraping is key for a homogenous batter. Then stir in the vanilla extract to bring the whole mix together.

Step 6: Combine Dry Ingredients & Coffee in Parts

Divide the dry ingredients into thirds. Add the first third into the wet mix with half of your coffee mixture and beat until just combined. Repeat with the second third and remaining coffee. Finish by adding the last third of the dry mix and give it a good stir until smooth—but don’t overmix. Your batter should have a fluid but not runny consistency.

Step 7: Bake to Perfection

Pour your batter evenly into the prepared pan, smoothing the top gently. Bake at 350°F (180°C) for 28–30 minutes. Check with a toothpick inserted in the center—it should come out with moist crumbs but no wet batter. I always test a little early because ovens vary. Once done, let the cake cool completely; frosting a warm cake can lead to melty messes!

Step 8: Make the Frosting

Microwave the chopped chocolate in 20-second intervals, stirring well after each, until smooth and fully melted. Set aside to cool slightly—too hot and it’ll ruin the frosting’s texture.

Next, beat your butter until fluffy. Gradually add powdered sugar on low speed, then crank up the mixer once incorporated and beat for 2–3 minutes until light and smooth. Then add the cocoa powder and mix well, scraping the bowl as needed.

Finally, pour in the cream and cooled melted chocolate. Beat until everything is combined and silky. Chill the frosting in the fridge for about 10 minutes before spreading—it firms up nicely and is much easier to work with.

Step 9: Frost and Enjoy

Spread the frosting over your cooled cake with a spatula or the back of a spoon, creating fun swirls to make it look inviting. Slice it up and get ready to enjoy one of the most moist, deeply chocolatey sheet cakes you’ll make (or eat!).

Top Tip

After making this Chocolate Mayonnaise Sheet Cake Recipe a bunch of times, I’ve learned a few tweaks that really make a difference. These tips will help you get that perfect moist crumb and luscious frosting every time.

Scrape Your Bowl Well: Frequently scraping your mixing bowl while incorporating eggs ensures an even batter and prevents clumps.
Don’t Skip the Coffee: Even though it’s subtle, the coffee powder emphasizes that rich chocolate flavor — trust me, it’s worth it!
Cooling is Key: Always cool the cake completely before frosting to avoid melting the frosting and making it runny.
Melt Chocolate Carefully: Using short bursts in the microwave and stirring prevents burnt chocolate, preserving the smooth texture for frosting.

How to Serve Chocolate Mayonnaise Sheet Cake Recipe

chocolate mayonnaise cake - Serving Suggestion

Garnishes

I usually keep it simple with this cake since it’s already pretty decadent. A few chocolate shavings sprinkled on top or a light dusting of cocoa powder adds a touch of elegance. Occasionally, I’ll toss on a handful of fresh raspberries or strawberries for a pop of color and a hint of tartness that balances the richness beautifully.

Side Dishes

Pair this cake with a tall glass of cold milk or a cup of strong coffee. For gatherings, I sometimes serve it alongside vanilla ice cream or whipped cream to add a creamy contrast. It’s always a crowd-pleaser that way.

Creative Ways to Present

For birthdays or celebrations, I like to dress up this sheet cake with colorful sprinkles or edible gold dust over the frosting. Another fun presentation trick is to slice it into rectangles and stack them on a platter, decoratively drizzled with chocolate sauce and topped with fresh mint leaves. It elevates a humble sheet cake to an impressive dessert display.

Make Ahead and Storage

Storing Leftovers

Once baked, I usually leave the cake in the pan, cover it tightly with plastic wrap, and store it at room temperature if I plan to eat it within a day. If I want it to last longer, I pop it into the fridge where it keeps well for up to 7 days. Make sure to bring the cake to room temperature before serving—it makes the frosting soft and the cake tender again.

Freezing

I’ve successfully frozen this cake both before and after frosting. For best results, wrap slices tightly in plastic wrap and foil to prevent freezer burn. When ready, thaw overnight in the fridge and bring to room temperature before serving. The texture stays surprisingly moist, making it a great make-ahead dessert.

Reheating

If you want a fresh-from-the-oven warm slice, I like to microwave individual pieces for about 15-20 seconds. It softens the frosting and makes the cake tender without drying it out. Just watch closely to avoid overheating.

Frequently Asked Questions:

Can I replace mayonnaise with something else in this recipe?

Mayonnaise is key here because it provides both moisture and fat which make the cake tender. You could try using sour cream or Greek yogurt as a substitute, but the texture may be slightly different. Mayonnaise’s unique blend of oil and eggs is what keeps the cake so moist and soft.

Why do you add coffee to a chocolate cake?

Adding instant coffee or espresso powder intensifies the chocolate flavor without making the cake taste like coffee. It brings out the deep, rich notes and adds complexity to the cake’s taste.

How do I know when the cake is done baking?

You want a toothpick inserted in the center to come out with moist crumbs, not wet batter. This indicates the cake is baked through but still incredibly moist inside. Keep an eye near the 28-minute mark—ovens can vary so testing a bit early helps prevent overbaking.

Can I make this cake dairy-free?

Since mayonnaise contains eggs and oil but not dairy, you can make this cake dairy-free by using a dairy-free butter substitute or oil to grease the pan and swapping the frosting ingredients for plant-based versions. Try coconut cream and dairy-free chocolate for the frosting to keep it luscious.

Final Thoughts

Honestly, this Chocolate Mayonnaise Sheet Cake Recipe feels like my little secret weapon for baking moist, chocolatey happiness that everyone loves. You might raise your eyebrows at the mayonnaise, but once you try it, you’ll be hooked on how tender and rich it turns out. I hope you enjoy baking and sharing it as much as I do—it’s perfect for bringing a little joy to the everyday or special moments alike.