🍫🍰 Moist Chocolate Sheet Cake
Ultra-moist, deeply chocolatey, and incredibly easy to make, this Moist Chocolate Sheet Cake is the kind of dessert that disappears fast. The combination of cocoa powder, buttermilk, and hot coffee creates a tender, rich crumb with an intense chocolate flavor, while the glossy chocolate frosting melts beautifully over the warm cake.
It’s simple enough for a weeknight dessert but special enough for birthdays, potlucks, holidays, and family celebrations.
⏱️ Recipe Information
Prep Time: 15 minutes
Bake Time: 28–32 minutes
Cooling Time: 20 minutes
Total Time: About 1 hour 10 minutes
Servings: 12–16
Difficulty: Easy
Method: Oven-Baked
Pan: 9 × 13-inch (23 × 33 cm) baking pan
🛒 Ingredients
For the Chocolate Cake
- 220 g (1¾ cups) all-purpose flour
- 60 g (⅔ cup) unsweetened cocoa powder
- 250 g (1¼ cups) granulated sugar
- 1½ teaspoons baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
- 2 large eggs, room temperature
- 120 ml (½ cup) neutral vegetable oil
- 240 ml (1 cup) buttermilk
- 2 teaspoons vanilla extract
- 180 ml (¾ cup) hot coffee or hot water
For the Chocolate Frosting
- 115 g (½ cup) unsalted butter
- 60 g (⅔ cup) unsweetened cocoa powder
- 360 g (3 cups) powdered sugar, sifted
- 80 ml (⅓ cup) milk or heavy cream, plus more if needed
- 2 teaspoons vanilla extract
- ¼ teaspoon salt
- 60 g (½ cup) semi-sweet or dark chocolate, finely chopped — optional, for extra richness
👩🍳 Instructions
Make the Chocolate Cake
1. Prepare the Oven and Pan
Preheat your oven to 350°F (175°C).
Lightly grease a 9 × 13-inch (23 × 33 cm) baking pan.
For easier removal, line the bottom with parchment paper, leaving a little overhang along two sides.
2. Combine the Dry Ingredients
In a large mixing bowl, whisk together the:
- Flour
- Cocoa powder
- Granulated sugar
- Baking powder
- Baking soda
- Salt
Break up any cocoa lumps as you whisk.
3. Combine the Wet Ingredients
In a separate bowl, whisk together the eggs, vegetable oil, buttermilk, and vanilla extract until smooth.
4. Combine the Batter
Pour the wet ingredients into the dry ingredients.
Whisk gently until just combined.
The batter will be fairly thick at this stage.
Don’t overmix.
5. Add the Hot Coffee
Slowly pour in the hot coffee or hot water, whisking gently as you go.
The batter will become noticeably thinner. This is exactly what you want.
Hot coffee intensifies the chocolate flavor without making the cake taste strongly of coffee. If preferred, use hot water instead.
6. Bake
Pour the batter into the prepared baking pan.
Smooth the surface with a spatula.
Bake for 28–32 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.
Avoid overbaking—the cake should remain moist and tender.
7. Cool the Cake
Place the cake on a wire rack and allow it to cool in the pan for approximately 15–20 minutes.
The cake should still be slightly warm when you frost it, but not piping hot.
🍫 Make the Chocolate Frosting
8. Melt the Butter
Place the butter in a medium saucepan over low heat.
Allow it to melt completely.
Remove from the heat.
9. Add the Cocoa
Whisk the cocoa powder into the melted butter until completely smooth.
If using chopped chocolate, add it now and stir until melted.
10. Add the Powdered Sugar
Gradually whisk in the sifted powdered sugar, alternating with the milk or heavy cream.
Start with a small amount of liquid and add more as needed.
Add the vanilla extract and salt.
Whisk until the frosting is smooth, glossy, and spreadable.
If the frosting is too thick, add milk 1 tablespoon at a time. If it’s too thin, add a little more powdered sugar.
11. Frost the Cake
Pour the warm chocolate frosting over the slightly warm cake.
Use an offset spatula or the back of a spoon to spread it evenly across the entire surface.
Allow the frosting to sit for 10–15 minutes so it can begin to set.
12. Slice and Serve
Once the frosting has set slightly, cut the cake into 12–16 squares.
Serve as is, or add a scoop of vanilla ice cream, whipped cream, or fresh berries.
⭐ Chef’s Tips
Use room-temperature eggs: They blend more easily into the batter and help create an even texture.
Don’t skip the hot liquid: Hot coffee or water helps bloom the cocoa and creates a particularly rich chocolate flavor.
Don’t overmix: Once the flour is incorporated, mix only until combined.
Don’t overbake: A few moist crumbs on a toothpick are perfect. A completely clean toothpick can mean the cake has gone too far.
Frost while slightly warm: A slightly warm cake allows the frosting to spread beautifully and creates a soft, almost fudge-like layer.
Use Dutch-process cocoa if desired: It gives a darker, smoother chocolate flavor, although regular unsweetened cocoa also works well.
For the smoothest frosting: Sift the powdered sugar before adding it.
🍫 Easy Variations
Chocolate Peanut Butter Sheet Cake
Spread a thin layer of creamy peanut butter over the cooled cake before adding the chocolate frosting.
Chocolate Coconut Cake
Add ½ cup shredded coconut to the batter and sprinkle toasted coconut over the frosting.
Chocolate Raspberry Cake
Spread a thin layer of raspberry jam over the cake before frosting and garnish with fresh raspberries.
Mocha Chocolate Cake
Use strong hot coffee in the batter and add ½ teaspoon espresso powder to the frosting.
Double Chocolate Sheet Cake
Fold ¾ cup (130 g) chocolate chips into the batter before baking.
Chocolate Mint Cake
Add ½ teaspoon peppermint extract to the frosting and decorate with finely chopped chocolate-mint candies.
🍨 Serving Suggestions
Serve this cake with:
- Vanilla ice cream
- Whipped cream
- Fresh strawberries
- Fresh raspberries
- Chocolate shavings
- Chopped toasted nuts
- Caramel sauce
- Extra chocolate sauce
For a simple presentation, dust the finished frosting with a tiny amount of cocoa powder or add a few chocolate curls.
🧊 Storage
Cover the cake tightly and store at room temperature for up to 2 days if your kitchen is cool.
For longer storage, refrigerate for up to 5 days.
Allow refrigerated slices to sit at room temperature for about 20–30 minutes before serving for the softest texture.
❄️ Freezing
The unfrosted cake can be frozen for up to 2 months.
Wrap it tightly in plastic wrap followed by aluminum foil.
Thaw overnight in the refrigerator, then bring to room temperature before frosting.
Frosted slices can also be individually wrapped and frozen for up to 1 month.
🍫🍰 Final Result
This Moist Chocolate Sheet Cake has a beautifully tender crumb, deep cocoa flavor, and an irresistible creamy chocolate frosting.
The buttermilk keeps it soft, hot coffee intensifies the chocolate, and the glossy frosting adds the perfect fudgy finish.
One pan, simple ingredients, incredibly moist chocolate cake — exactly the kind of dessert everyone comes back for. 🍫✨