Description
This decadent Chocolate Mayonnaise Sheet Cake combines rich cocoa and coffee flavors with moistness achieved by mayonnaise, baked in a single 9x13-inch pan and topped with a luscious chocolate frosting. Perfect for gatherings or a special dessert treat.
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: Preheat the oven to 350°F (180°C). Brush a 9x13-inch sheet pan with butter and set aside.
- Mix Dry Ingredients: In a medium bowl, combine all-purpose flour, cocoa powder, baking powder, baking soda, and salt until evenly mixed. Set aside.
- Dissolve Coffee: In a glass measuring cup, stir instant coffee powder into hot water until dissolved. Set aside.
- Cream Mayonnaise and Sugars: In a large mixing bowl, beat mayonnaise, white sugar, and brown sugar with an electric mixer until pale and creamy.
- Add Eggs and Vanilla: Add eggs one at a time to the mayonnaise mixture, beating well after each addition. Scrape down sides of the bowl periodically. Then beat in vanilla extract.
- Combine Wet and Dry Ingredients: Add the dry ingredients to the wet mixture in thirds, alternating with half of the hot coffee each time. Beat until combined after each addition. The batter should be neither stiff nor runny.
- Bake the Cake: Pour batter into the prepared pan and bake for 30 minutes or until a toothpick inserted in the center comes out with moist crumbs. Allow cake to cool completely before frosting.
- Melt Chocolate for Frosting: Melt chopped chocolate in the microwave in 20-second intervals, stirring after each, until smooth. Let cool slightly.
- Beat Butter and Sugar: Beat unsalted butter in a large bowl until creamy and fluffy. Gradually add powdered sugar starting on low speed and increase to high, beating 2 to 3 minutes.
- Add Cocoa Powder: Beat in cocoa powder until smooth, scraping down bowl sides as needed.
- Add Cream and Chocolate: Add heavy cream and cooled melted chocolate to the frosting, beating until well combined. Refrigerate for 10 minutes to set.
- Frost the Cake: Spread the frosting evenly over the cooled cake using a spatula or the back of a spoon to create swirls.
- Serve and Store: Slice and serve. Store the unfrosted cake covered at room temperature for 1 day or refrigerated for up to 7 days. Frosted cake can be refrigerated for 3 days; bring to room temperature before serving.
Notes
- Use Dutch-processed cocoa powder for a richer flavor and darker color.
- Dissolving instant coffee in hot water enhances the chocolate flavor without adding coffee taste.
- Allow melted chocolate to cool before adding to the frosting to avoid melting the butter.
- Let the frosted cake come to room temperature before slicing for easier cutting.
- Mayonnaise adds moisture and tang, but use a good quality mayonnaise for best taste.
- The cake can be stored covered at room temperature or refrigerated depending on desired freshness.
- Use a toothpick test to avoid overbaking for a moist texture.
Nutrition
- Serving Size: 1 slice
- Calories: 390 kcal
- Sugar: 35 g
- Sodium: 210 mg
- Fat: 22 g
- Saturated Fat: 9 g
- Unsaturated Fat: 11 g
- Trans Fat: 0.2 g
- Carbohydrates: 45 g
- Fiber: 3 g
- Protein: 4 g
- Cholesterol: 50 mg
