Description
This Chocolate Mayonnaise Sheet Cake is a moist, rich, and fudgy dessert made with mayonnaise for an incredibly tender crumb. Featuring a luscious cocoa and instant coffee-infused batter topped with a creamy chocolate frosting, it's perfect for gatherings or any chocolate craving.
Ingredients
Scale
For the cake
- 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
For the frosting
- 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
Instructions
- Preheat and prepare pan: Preheat the oven to 350°F (180°C). Brush a 9x13-inch baking pan with butter and set aside.
- Mix dry ingredients: In a medium bowl, whisk together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt until evenly combined. Set aside.
- Dissolve coffee: In a glass measuring cup, stir the instant coffee powder into hot water until dissolved. Set aside.
- Beat mayonnaise and sugars: In a large mixing bowl, use an electric mixer to beat the mayonnaise with white and brown sugars until pale and creamy.
- Add eggs and vanilla: Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl occasionally. Pour in the vanilla extract and mix to incorporate.
- Combine wet and dry ingredients: Add the dry ingredients in three parts, alternating with the hot coffee in two halves. Beat the first third of dry ingredients with half the coffee, then the second part of dry ingredients with the remaining coffee. Finally, add the last third of dry ingredients and mix until just combined. The batter should be neither stiff nor runny.
- Bake the cake: Pour the batter into the prepared pan and bake for 30 minutes or until a toothpick inserted in the center comes out with moist chocolate crumbs. Let the cake cool completely before frosting.
- Melt chocolate for frosting: In a microwave-safe bowl, melt the chopped chocolate in 20-second intervals, stirring between each until smooth (about 40 to 70 seconds). Let it cool slightly.
- Beat butter and sugar: Using an electric mixer, beat the butter until creamy and fluffy. Gradually add powdered sugar, starting on low speed and increasing to high, beating for 2 to 3 minutes until well combined.
- Add cocoa powder: Mix in the cocoa powder, beating until smooth. Scrape down the bowl sides as needed.
- Add cream and melted chocolate: Pour in the heavy cream and cooled melted chocolate, then beat until fully incorporated. Chill the frosting in the refrigerator for 10 minutes before spreading.
- Frost the cake: Spread the frosting evenly over the cooled cake, creating swirls with a spatula or spoon.
- Serve and store: Slice and serve the cake. Keep the unfrosted cake covered at room temperature for 1 day or refrigerated for up to 7 days. The frosted cake can be refrigerated for up to 3 days; bring to room temperature before slicing to soften the frosting.
Notes
- Use Dutch processed cocoa powder for a richer chocolate flavor and smoother texture.
- The mayonnaise adds moisture and tenderness to the cake; do not substitute with other spreads.
- If you don’t have instant coffee/espresso powder, you can omit it, but it enhances the chocolate flavor dramatically.
- Make sure the melted chocolate for the frosting is cooled before mixing to prevent melting the butter.
- Bring the frosted cake to room temperature before slicing for the best texture.
- Store leftover cake covered to maintain freshness and prevent drying.
Nutrition
- Serving Size: 1 slice (1/12 of cake)
- Calories: 410 kcal
- Sugar: 38 g
- Sodium: 300 mg
- Fat: 22 g
- Saturated Fat: 9 g
- Unsaturated Fat: 11 g
- Trans Fat: 0 g
- Carbohydrates: 52 g
- Fiber: 4 g
- Protein: 5 g
- Cholesterol: 55 mg
