Chocolate Sheet Cake

Sheet cakes are making a comeback. There’s something about a sheet cake, old fashioned and all American. It reminds me of my childhood and summer at the same time. Maybe because I have a summer birthday and I always had a sheet cake from the local market decorated with Cinderella. Whether homemade or store bought, I’m sure this cake brings back fond memories for you too.

The best part about a sheet cake, the simplicity – ease of frosting and serving it straight from the pan. There are no decorating skills required. Just a simple shake of sprinkles, or in my case, using petals from edible flowers like pansies. Actually, no adornment is equally as pretty.

This is my go-to cake for summer parties, block parties, potluck parties and of course…birthday parties.

This deep, dark chocolate cake recipe is my absolute favorite and can also be used for cupcakes or a layer cake. I’m including two frosting options, a mocha swiss buttercream and an American buttercream – the latter being much quicker.

I’ve had so many requests for the mocha buttercream and all of the credit goes to Zoë Bakes. It’s almost like eating a thick layer of mousse. The American buttercream is easy to make and delicious as well. I am sure this sheet cake will become one of your new favorites too.

INGREDIENTS (Serves: a crowd as a sheet cake, 24 cupcakes, or an 8” round layer)

• 3/4 C plus 2 T cocoa powder, (not dutch processed)
• 1/2 C boiling water
• 1 C buttermilk
• 1 3/4 C all purpose flour
• 1 1/4 t baking soda
• 1/4 t baking powder
• 1/4 t salt
• 1 1/2 sticks unsalted butter
• 1 1/2 C granulated sugar
• 2 large eggs
• 1 t vanilla extract

INSTRUCTIONS: 1/2 Sheet Pan, measuring 11” x 15”

1. Pre-heat the oven to 350 degrees. Butter a 1/2 sheet pan. Set aside.
2. Put the cocoa powder in a medium heatproof bowl. Add boiling water and whisk until a smooth paste forms. Whisk in buttermilk until combined.
3. In a medium bowl, sift the flour with the baking powder, baking soda and salt.
4. In a large bowl, using an electric mixer, beat the butter with the granulated sugar until light and fluffy, about 3 minutes. Beat in the eggs and vanilla. Then beat in the dry ingredients in two batches alternating with the cocoa mixture. Pour into the pan.
5. Bake approximately 20-25 minutes until done. Cool completely.  

American Chocolate Buttercream:

• 3 sticks unsalted butter, firm but not cold
• pinch of salt
• 4 C powdered sugar, sifted
• 1/2 t vanilla
• 6 oz bittersweet chocolate, melted and cooled to room temperature
• 4 T whole milk

1. In a bowl of a mixer with a flat beater, beat the butter and salt until light and fluffy, about 2 minutes. Reduce the speed until low, gradually beat in the sugar until incorporated. Add the vanilla and beat until smooth and creamy. Scrape down the sides. Add the chocolate and beat on medium speed until smooth and creamy.
2. If it’s too dense, add the milk 1 T at a time. Do not over mix.

Mocha Swiss Buttercream (adapted from Zoë Bakes)

• 2 extra-large eggs, room temperature
• 2 extra large egg yolks, at room temperature
• 1/4 C granulated sugar
  –
• 1 1/4 C granulated sugar
• 1/2 C water
• 1/4 t cream of tartar
  –
• 1 lb (4 sticks) unsalted butter, softened
• 6 oz. bittersweet chocolate, very finely chopped, melted and cooled
• 2 t instant espresso powder
• 1 T water

1. In a small saucepan, with a candy thermometer, bring the 1 1/4 C sugar, water, cream of tartar to a boil over medium high heat. Keep a bowl of water with a pastry brush nearby to wipe down the side of the pan if any sugar crystals attach. The sugar needs to boil until it reaches 242 degrees, which should take several minutes.
2. Meanwhile, place the eggs, egg yolks and 1/4 C sugar in the bowl of a standing mixer, and whip with a whisk on medium speed until they are thick, pale and makes a ribbon when lifted.
3. Once the sugar reaches 242, slowly pour it in the bowl of whipped egg yolks while it is beating. Be sure and pour it down the side. (If you do it in the middle, it gets stuck to the whisk and splatters.) Beat until cool. About 8 minutes.
4. Add the butter 2 tablespoons at a time. The buttercream goes through a stage of being soupy, but do not worry, it will come together. Just keep adding each piece of butter until it’s incorporated.
5. Mix espresso with water until dissolved.
6. Add melted and cooled chocolate and espresso. The finished buttercream will be smooth and silky.

This can be made ahead. Just refrigerate, bring to room temperature and whisk on low until smooth.