Name: Classic Chocolate Sheet Cake
Prep time: 15 min
Cook time: PT-491875H8M28S
Total time: PT-491875H8M28S
Cuisine: Southern
Ingredients: 2 cups (250g) all-purpose flour; 2 cups (400g) granulated sugar; 1/4 tsp salt; 1 tsp baking soda; 1 cup (226g) unsalted butter; 1/4 cup (25g) unsweetened cocoa powder; 1 cup (240ml) water; 1/2 cup (120ml) buttermilk; 2 large eggs; 1 tsp vanilla extract; 1/2 cup (113g) unsalted butter (for frosting); 1/4 cup (25g) unsweetened cocoa powder (for frosting); 6 tbsp whole milk; 1 tsp vanilla extract (for frosting); 3 1/2–4 cups (420–480g) powdered sugar, sifted; Optional: 1 cup chopped pecans or walnuts

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This classic chocolate sheet cake is rich, moist, and topped with a pourable warm cocoa frosting that sets into a smooth, fudgy layer. It’s an old-fashioned favorite that comes together quickly and feeds a crowd—perfect for potlucks, birthdays, or any time I want a nostalgic chocolate fix.

Classic Chocolate Sheet Cake

Ingredients

(Tip: You'll find the full list of ingredients and measurements in the recipe card below.)

For the Cake :

2 cups (250g) all-purpose flour

2 cups (400g) granulated sugar

¼ teaspoon salt

1 teaspoon baking soda

1 cup (2 sticks / 226g) unsalted butter

¼ cup (25g) unsweetened cocoa powder

1 cup (240ml) water

½ cup (120ml) buttermilk

2 large eggs

1 teaspoon vanilla extract

Warm Chocolate Frosting:

½ cup (1 stick / 113g) unsalted butter

¼ cup (25g) unsweetened cocoa powder

6 tablespoon whole milk

1 teaspoon vanilla extract

3½–4 cups (420–480g) powdered sugar, sifted

Optional: 1 cup chopped pecans or walnuts (classic Southern style)

Directions

Preheat & Prep:

I preheat my oven to 350°F (175°C) and grease and flour a 13x18-inch sheet pan (or a 9x13 pan if I want a thicker cake—just increase the bake time).

Make the Cake Batter:

In a large bowl, I whisk together flour, sugar, baking soda, and salt.

Then, in a saucepan, I combine butter, cocoa powder, and water, bringing it to a gentle boil until smooth. I pour this hot mixture into the dry ingredients and stir to combine.

Separately, I whisk buttermilk, eggs, and vanilla, then add this to the batter and stir until fully smooth.

Bake:

I pour the batter into the prepared pan and spread it evenly. For a sheet pan, I bake it for 20–22 minutes. For a 9x13 pan, I bake it for 30–35 minutes, or until a toothpick comes out clean.

While the cake is baking, I start on the frosting so it’s ready to pour over the warm cake.

Make the Warm Frosting:

In a saucepan, I melt butter with cocoa powder and milk over medium heat. Once it simmers, I remove it from heat and stir in vanilla and sifted powdered sugar until smooth. If I’m using nuts, I stir them in last.

Frost the Cake:

I pour the warm frosting over the hot cake and quickly spread it with a spatula before it sets.

Servings and timing

This recipe makes about 16–20 servings, depending on how I cut the cake. It takes around 15 minutes to prep, 20–35 minutes to bake (depending on pan size), and about 10 minutes to make and spread the frosting. Total time: approximately 45–60 minutes.

Variations

I swap the nuts for toasted coconut flakes when I want something different.

For a mocha twist, I add ½ teaspoon instant espresso powder to the cocoa mixture.

I sometimes make it with dark cocoa powder for an extra rich flavor.

I’ve halved the recipe and baked it in an 8x8-inch pan with great results.

I’ve also used gluten-free all-purpose flour with success.

Storage/Reheating

I store the cake covered at room temperature for up to 3 days. If I want it to last longer, I refrigerate it and let it come to room temperature before serving. It also freezes well—I wrap individual slices and freeze them for up to 2 months.

FAQs

How do I know when the cake is done baking?

I check for doneness by inserting a toothpick in the center of the cake—if it comes out clean or with a few moist crumbs, it’s ready.

Can I use Dutch-processed cocoa powder?

Yes, I’ve used Dutch-processed cocoa in this recipe. It gives a deeper flavor, but the cake still rises well thanks to the baking soda.

Can I make this cake ahead of time?

Absolutely. I often bake the cake a day in advance and frost it while it’s still warm. It stays moist and delicious for days.

What’s the difference between a sheet cake and regular cake?

A sheet cake is typically baked in a shallow, large pan and frosted in the pan. It’s thinner and ideal for serving a crowd. Regular cakes are usually taller and made in round or loaf pans.

Is the frosting supposed to be pourable?

Yes! I pour the frosting over the warm cake so it spreads easily and sets into a smooth, fudgy layer. That’s what gives it its classic texture.

Conclusion

This classic chocolate sheet cake is one of those timeless desserts I return to again and again. It’s easy, comforting, and crowd-pleasing. Whether I make it for a party or just to satisfy a craving, it never disappoints—and the warm chocolate frosting is the icing on the cake, literally.

📖 Recipe:

Classic Chocolate Sheet Cake

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Author: Cheryl
Total Time: 45–60 minutes
Yield: 16–20 servings
Diet: Vegetarian

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Description

This classic chocolate sheet cake is rich, moist, and topped with a pourable warm cocoa frosting that sets into a smooth, fudgy layer. A Southern-style favorite perfect for potlucks, birthdays, or anytime you need a nostalgic chocolate treat.

Instructions

Preheat oven to 350°F (175°C) and grease and flour a 13x18-inch sheet pan (or a 9x13 pan for a thicker cake).
In a large bowl, whisk together flour, sugar, baking soda, and salt.
In a saucepan, combine butter, cocoa powder, and water. Bring to a gentle boil until smooth.
Pour hot cocoa mixture into dry ingredients and stir to combine.
In a separate bowl, whisk buttermilk, eggs, and vanilla extract. Add to the batter and stir until smooth.
Pour batter into prepared pan and spread evenly. Bake for 20–22 minutes for a sheet pan or 30–35 minutes for a 9x13 pan, until a toothpick comes out clean.
While the cake bakes, make the frosting: In a saucepan, melt butter with cocoa powder and milk over medium heat. Once it simmers, remove from heat and stir in vanilla and powdered sugar until smooth. Stir in nuts if using.
Immediately pour warm frosting over hot cake and spread quickly before it sets.
Let cool slightly before slicing. Serve warm or at room temperature.