Fudgy Chocolate Sheet Cake with Vanilla Buttercream

A slice of moist chocolate sheet cake with vanilla buttercream.

5 from 2 votes

Fudgy Chocolate Sheet Cake with Vanilla Buttercream

A fudgy and moist chocolate sheet cake frosted with vanilla buttercream! This simple cake is the perfect birthday party cake. It's really easy to whip up and you don't even need a mixer for the cake.

Prep Time20

Cook Time35

Total Time55

Course: Dessert

Cuisine: American

Diet: Vegetarian

Servings: slices

Calories: 603kcal

Author: Ella Gilbert

Equipment

1 9x13-inch cake pan

Ingredients

Chocolate Cake

¾ cup cocoa powder dutch processed
1 ¾ cups granulated sugar
¾ teaspoon vanilla extract
¾ teaspoon kosher salt
2 large eggs room temperature
2 cups all purpose flour
2 teaspoon baking soda
1 teaspoon baking powder
1 cup buttermilk room temperature
½ cup vegetable oil
1 cup very hot water
1 teaspoon espresso powder optional

Vanilla Buttercream

2 sticks unsalted butter room temperature
4 cups confectioners' sugar
3 teaspoons vanilla extract or 1 tablespoon vanilla bean paste
¼ teaspoon kosher salt
¼ cup whole milk

Metric - US Customary

Instructions

Make Cake

Preheat your oven to 350°F/175°C. Butter or grease a 9x13-inch baking pan and line with parchment paper. I find it easiest to make a 'sling' so you can easily remove the cake later.
Combine the flour, cocoa powder, sugar, baking powder, baking soda, and salt in a large bowl with a whisk.
¾ cup cocoa powder, 1 ¾ cups granulated sugar, 2 cups all purpose flour, 2 tsp baking soda, 1 tsp baking powder, ¾ tsp kosher salt
In a large jug, whisk together the buttermilk, oil, eggs, and vanilla extract.
¾ tsp vanilla extract, 1 cup buttermilk, ½ cup vegetable oil, 2 large eggs
Slowly pour in the ingredients from the large jug and mix until just combined.
Mix the espresso powder with the hot water (if using). Slowly add the hot coffee and mix. Your batter will be very thin and it makes a lot of cake batter!
1 cup very hot water, 1 teaspoon espresso powder
Pour the batter into the prepared pan. Bake for 35-40 minutes, until a toothpick comes out clean when inserted
Let the cake cool completely.

Make Frosting

In a stand mixer fitted with the paddle attachment, beat the butter and confectioners' sugar together on low speed until well combined.
2 sticks unsalted butter, 4 cups confectioners' sugar
Increase the speed to medium-high and beat for 2 minutes until it becomes very thick.
Stop the mixer and add the salt and vanilla extract into the bowl. Beat on medium-high speed for another 2 minutes.
3 teaspoons vanilla extract, ¼ teaspoon kosher salt
Turn the mixer to your lowest speed and pour in the milk. Beat until it becomes very creamy and spreadable.
¼ cup whole milk
Spread the frosting on top of the cake. I like to save some of the vanilla buttercream and pipe a shell border around the cake!

Notes

My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. I have provided a conversion to US cups but please note that I haven’t tested the recipe with this method. Just click on ‘US Customary’ above the ingredients to see the cup measurements.

I make sure that all of my ingredients are at room temperature before I start the recipe, so pull out all of the ingredients before you start baking.

Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.

Buttermilk: If you don’t have buttermilk, replace it with an equal amount of sour cream or full fat yogurt. You can also make your buttermilk, for every cup of buttermilk add 1 tablespoon of lemon juice to 1 cup of milk and let sit for 5 minutes.

Cocoa Powder: make sure to use Dutch-processed cocoa powder and not natural cocoa powder. Not sure what type you have? Check the ingredients! If it mentions alkali or acidity regulators, it's Dutch-processed cocoa powder.

Vegetable Oil: Use an unflavoured oil like canola oil if you don’t have vegetable oil.

Storage: Keep tightly wrapped in the fridge for up to 5 days. Let it come to room temperature before eating.

Making Ahead: You can make the cake ahead of time. Bake and then once completely cooled, wrap in plastic wrap tightly. Store in the fridge for up to 2 days or in the freezer for up to 2 months. If frozen, allow to defrost and come to room temperature before frosting the cake.

Nutrition