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 nostalgic and downright irresistible about a sheet cake that’s rich, moist, and perfectly chocolatey. This Chocolate Mayonnaise Sheet Cake Recipe might sound unusual at first, but trust me—it’s a total game-changer. The mayonnaise keeps the cake incredibly tender while the frosting is lusciously smooth. Let me tell you why it’s worth adding to your baking rotation.

A glass tray holds a rich, dark brown cake with a thick, smooth layer of lighter brown frosting on top that has soft swirls and peaks. Three square pieces have been cut from the cake, showing the dense, moist texture of the dark cake underneath the glossy, creamy frosting. The cake sits on a white marbled surface with some crumbs around the tray edges. 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

I’ve made many chocolate cakes in my kitchen, but this Chocolate Mayonnaise Sheet Cake Recipe stands out because it combines simplicity with a texture so moist it’s like biting into a velvet cloud of chocolate. Plus, the coffee-infused cocoa deepens the flavor, making it irresistible whether it’s a casual family dessert or a special occasion.

Unbelievably Moist Texture: Thanks to the mayonnaise, this cake stays tender and rich without being greasy or heavy.
Deep Chocolate Flavor: Using Dutch-processed cocoa and instant coffee powder layers in a complex cocoa richness you don’t find in every chocolate cake.
Easy to Make: You don’t need any fancy equipment or complicated techniques—just a mixing bowl and a pan.
Decadent, Smooth Frosting: The combination of melted chocolate and cocoa powder creates a luscious finish that’s rich but not overpowering.

Ingredients & Why They Work

This recipe beautifully balances classic chocolate cake ingredients with an unexpected twist—mayonnaise. Each ingredient plays a special role, from giving that chocolate punch to the moist crumb you’ll adore.

Flat lay of a small white ceramic bowl of all-purpose flour, a small white ceramic bowl of unsweetened Dutch processed cocoa powder, a small white ceramic bowl of light brown baking powder, a small white ceramic bowl of light brown baking soda, a small white ceramic bowl of coarse salt, a small white ceramic bowl of hot water with dissolved instant coffee powder, two large whole brown eggs with clean shells, a small white ceramic bowl of white granulated sugar, a small white ceramic bowl of packed brown sugar, a small white ceramic bowl of creamy mayonnaise, a small white ceramic bowl of amber vanilla extract, a small white ceramic bowl of finely chopped dark semisweet chocolate, a small white ceramic bowl of unsalted butter cubes, a small white ceramic bowl of powdered sugar, a small white ceramic bowl of heavy cream 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

All-purpose flour: Forms the structure of the cake, choose a good quality brand with a medium protein content for the best results.
Unsweetened Dutch processed cocoa powder: This adds that rich chocolate flavor with less acidity, making the cake taste smoother.
Baking powder & baking soda: They work together to give your cake a nice rise and light crumb.
Salt: Enhances the chocolate and balances sweetness.
Instant coffee powder or espresso powder: It might surprise you, but this really boosts the chocolate flavor without leaving a coffee taste.
Eggs: Help bind ingredients and add richness.
Sugar (white and brown): The brown sugar brings a subtle molasses depth, while white sugar keeps the sweetness bright.
Mayonnaise: The star secret! It adds moisture and richness due to the oil and eggs inside but keeps the cake light.
Vanilla extract: Brings warmth and rounds out the flavor.
Semisweet or bittersweet chocolate (for frosting): Adds a deep chocolate kick for the frosting.
Unsalted butter: Makes the frosting creamy and smooth.
Powdered sugar: Sweetens the frosting without graininess.
Heavy cream: Adds silkiness and a spreadable texture to the frosting.

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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

This cake is a nice blank canvas, so I love encouraging you to make it your own. Whether you want to swap out the coffee powder to skip caffeine or add a pinch of cayenne for an unexpected twist, it all works really well.

Variation: I once tried adding a handful of chopped toasted pecans to the batter for extra texture and it complemented the chocolate beautifully without making the cake too heavy.
Dietary tweak: For a dairy-free option, substitute the butter and heavy cream in the frosting with coconut oil and coconut cream.
Seasonal touch: Try swirling in raspberry jam between layers or topping with fresh berries for a fruity brightness.

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

A thick slice of dark chocolate cake with two layers is placed in the center of a round white plate with a gold rim. The bottom layer is a dense, moist dark brown cake with a rough texture, while the top layer is a smooth and creamy light brown chocolate frosting, spread unevenly with some soft peaks. A shiny gold fork rests diagonally on the lower left side of the plate. In the blurred background, two more slices of the same cake on white plates with gold rims sit on a white marbled surface, creating a cozy dessert setting. photo taken with an iphone --ar 2:3 --v 7

Step 1: Prep Your Pan and Oven

Before getting into the batter, preheat your oven to 350°F (180°C) and lightly butter a 9x13-inch sheet pan. I always make sure to grease all the corners and edges so the cake slides right out later, which makes life easier.

Step 2: Mix Dry Ingredients Together

In a medium bowl, whisk together the all-purpose flour, Dutch processed cocoa powder, baking powder, baking soda, and salt. Give it a good mix so everything’s evenly combined and you won’t get pockets of soda or cocoa later in the batter.

Step 3: Dissolve Instant Coffee in Hot Water

Pour your hot water over the instant coffee powder in a glass measuring cup and stir until it dissolves smoothly. This step awakens the chocolate flavor without a noticeable coffee taste – trust me, you want this step.

Step 4: Beat Mayonnaise and Sugars

Using an electric mixer, beat the mayonnaise with the white and brown sugars just until it’s pale and creamy. This mixture looks a little odd at first but it’s key to a moist cake. It might seem thick, but keep going.

Step 5: Incorporate Eggs and Vanilla

One at a time, add the eggs to the mixture, beating well after each addition. Remember to scrape down the sides of your bowl often to keep everything evenly mixed. Finally, pour in the vanilla extract and mix it through.

Step 6: Combine Wet and Dry Ingredients

Add the dry ingredients to the wet eggs and mayo mixture in three parts. Alternate by adding half of the hot coffee mix with the first two additions of dry ingredients to keep the batter balanced. Give the batter a good stir between steps but don’t overmix it – it should be smooth but not runny.

Step 7: Bake Until Just Right

Pour the batter into the prepared pan and bake for 28 to 30 minutes. I always check with a toothpick around 28 minutes; you’re looking for moist crumbs, not wet batter sticking to the toothpick. Overbaking dries out the cake, so keep an eye.

Step 8: Make the Lush Frosting

Melt the chopped chocolate in short bursts in the microwave, stirring between intervals until velvety smooth, then set aside to cool slightly. Meanwhile, beat the butter until fluffy, gradually add powdered sugar on low speed, then crank it up for a few minutes until silky. Mix in the cocoa powder, then add the heavy cream and cooled chocolate and beat until perfectly spreadable. Chill for 10 minutes before frosting the cake.

Step 9: Frost and Finish

Once the cake is completely cool, spread the frosting evenly over the top. I like to create swirls and waves with my spatula for a homemade look that invites you to dig in.

Top Tip

Making this Chocolate Mayonnaise Sheet Cake Recipe took a few tries before I nailed the perfect moist texture and rich flavor balance. These tips saved me from common pitfalls and helped the cake come out just right every time.

Don’t Skip the Coffee: Even if you avoid caffeine, that little bit of instant coffee powder enhances the chocolate flavor without making it taste like coffee.
Careful on Baking Time: Overbaking will dry out the cake. I rely on the toothpick test and err on the side of slightly underdone—it finishes cooking as it cools.
Frost When Cake is Fully Cool: Frosting on a warm cake melts and becomes runny. Let it rest completely for a clean, smooth finish.
Cool the Melted Chocolate: Beat the frosting only after the chocolate has cooled to avoid curdling or graininess.

How to Serve Chocolate Mayonnaise Sheet Cake Recipe

chocolate mayonnaise cake - Serving Suggestion

Garnishes

I keep garnishes simple—a dusting of powdered sugar or a sprinkle of chopped toasted nuts works beautifully. For a festive feel, I’ve topped it with fresh raspberries or a few chocolate shavings to match the frosting.

Side Dishes

This cake pairs wonderfully with a scoop of vanilla ice cream or a dollop of whipped cream. A warm cup of coffee or a glass of cold milk rounds out the experience perfectly.

Creative Ways to Present

For birthdays or gatherings, I’ve tried stacking two sheet cakes with frosting in between for a layered version. Also, cutting into small squares and serving on pretty platters with berries creates an elegant dessert spread that disappears fast!

Make Ahead and Storage

Storing Leftovers

Once baked, I like to keep the cake in the pan covered tightly with plastic wrap at room temperature for a day or refrigerate for up to a week. Just remember to bring it back to room temp before slicing if frosted—it’s easier to cut and tastes better.

Freezing

This cake freezes well unwraped or in an airtight container. Freeze it before frosting for best texture. Thaw overnight in the fridge and frost fresh for a “just baked” experience even days later.

Reheating

If you want a warm slice, microwave single servings for about 15 seconds. The frosting softens and the cake feels freshly baked. For larger pieces, let it warm at room temp for 20 minutes before serving.

Frequently Asked Questions:

What does mayonnaise do in this chocolate cake?

Mayonnaise might seem like an odd ingredient in cake, but it’s actually a clever way to add moisture and richness. Because mayonnaise contains oil and eggs, it keeps the crumb soft and tender without making the cake greasy.

Can I omit the coffee powder?

While you can skip the instant coffee or espresso powder, it’s highly recommended because it enhances and deepens the chocolate flavor without adding any coffee taste. If you must omit it, consider substituting with hot water to keep the liquid balance.

How do I know when the cake is done baking?

Use a toothpick inserted into the center of the cake. It’s done when the toothpick comes out with moist crumbs but no wet batter. Be careful not to overbake, as that dries the cake out.

Can this cake be made gluten-free?

Yes! You can substitute the all-purpose flour with a gluten-free baking flour blend, but make sure it contains xanthan gum or other binding agents to mimic gluten’s elasticity. The texture may be slightly different but should still be moist and delicious.

Final Thoughts

This Chocolate Mayonnaise Sheet Cake Recipe is a little secret I love sharing because it turns everyday ingredients into something truly special. The combination of simple prep, incredible texture, and rich flavor makes it a winner at gatherings or a comfort treat on any day. Give it a go—you might just find your new favorite chocolate cake.