High Altitude Chocolate Hostess Sheet Cake
This chocolate hostess sheet cake is a spin on the classic hostess cupcakes, with two layers of moist chocolate cake, filled with fluffy whipped vanilla buttercream, covered in rich chocolate ganache, and decorated with the iconic curly white icing on top. You’ll love this delicious homemade version of a classic childhood treat!
All recipes on Curly Girl Kitchen are developed for high altitude at 5,280 feet. See FAQs for adjusting to higher or lower elevations.
Equipment
- 2 9x13 Baking Pans (or a rimmed 13x18 inch baking sheet)
- 12-Inch Disposable Piping Bag
- Coupler + Tip #3
- Stand Mixer with Paddle Attachment
Ingredients
Cake
- 2 cups all-purpose flour, fluffed, spooned and leveled
- 1 ¾ cups granulated sugar
- ¾ cup unsweetened Dutch-processed cocoa powder
- 2 tbsp instant espresso powder or instant coffee
- ¾ tsp baking soda
- ½ tsp baking powder
- 1 tsp coarse Kosher salt (if using table salt, use half the amount)
- 4 large eggs, room temperature
- 1 cup full fat sour cream, room temperature
- 1 cup whole milk, room temperature
- 1 cup vegetable oil
- 1 tbsp vanilla extract
Filling and Curly Icing
- ½ cup unsalted butter, softened to room temperature
- ½ cup vegetable shortening
- 2 ½ cups powdered sugar
- 1 tsp meringue powder, optional
- 1 ½ tsp vanilla extract
- ⅓ cup cold heavy whipping cream
- 1 tsp light corn syrup
Ganache
- 8 oz semi sweet or dark chocolate, chopped (or chocolate chips)
- 8 oz heavy whipping cream
Instructions
Cake
- Preheat the oven to 350 F, and position a rack in the center of the oven. Prep two 9x13 inch baking pans by spraying them with non-stick baking spray. Line the pans with a sheet of parchment baking paper, to ensure the cakes come out cleanly.Tip: If you don't have two 9x13 inch baking pans, you can use a rimmed 13x18 inch baking sheet instead (you must also line the baking sheet with parchment paper). Then cut the baked cake in half to stack and assemble the two halves. I have not tested the baking time for this option, though.
- In a large bowl, sift together the flour, sugar, cocoa powder, espresso powder, baking soda, baking powder and salt.
- In a separate bowl, whisk together the eggs, sour cream, milk, oil and vanilla, until well combined. Add the wet ingredients to the dry, and whisk the batter just until combined.
- Divide the batter between the pans. Bake the cakes for about 22-25 minutes, until the center springs back when lightly touched, and a toothpick or cake tester inserted in the center comes out clean.
- Set the pans on a cooling rack, and cool completely before assembling the cake.
Filling
- In the bowl of your stand mixer fitted with the paddle attachment, beat the softened butter with the shortening for one minute, until smooth.
- With the mixer on low, add the powdered sugar by spoonfuls, and the meringue powder, mixing until combined. Add the vanilla and the heavy whipping cream.
- Whip the buttercream on medium high speed for 4-5 minutes, stopping to scrape down the bowl several times, until light and fluffy. Turn the speed down to low and mix for one more minute.
- Remove 1/3 cup of the buttercream to another bowl, and set it aside to use for the curly icing on top. Stir in the corn syrup, which helps to make the buttercream flow more smoothly through a small piping tip.
Ganache
- When you're ready to assemble your cake, you can start on the ganache. Finely chop the chocolate (no bigger than 1/4 inch pieces), and scrape the chocolate into a bowl. You can also use semi-sweet chocolate chips, instead of chopping a bar of chocolate.
- In a saucepan, heat the cream over medium heat, just until hot and beginning to simmer around the edges.
- Pour the hot cream over the chocolate, let sit for 3 minutes, then stir with a spatula until it smooths out into a creamy ganache.
- Note: You can also make the ganache over a double boiler. Simply combine both the chocolate and cream in a heat proof bowl. Set the bowl over a saucepan of gently simmering water, making sure that the bottom of the bowl does not touch the water. Let the cream warm up and the chocolate melt, stirring with a spatula until smooth and creamy.
- Let the ganache cool at room temperature for five minutes, until it's thickened slightly.
Assembly
- You can assemble your cake on a baking sheet, cutting board, or any large serving plate. Begin by lifting one of the cakes out of the pan by the parchment paper. Because these cake layers are so large, they can easily break apart if you don't handle them carefully. Quickly, invert one of the cake layers onto the baking sheet, then peel off the parchment paper.
- Spread the buttercream over the cake, all the way to the edges, making it as smooth and even as possible.
- Quickly invert the second layer of cake over the buttercream, and peel the parchment paper off the cake.
- If needed, trim any uneven edges around the sides of the cake, and smooth out the buttercream around the sides.
Decorating
- Pour 1/3 of the warm ganache on top of the cake. Use an offset icing spatula to spread the ganache out into a very thin layer on top of the cake. Nudge it over the edges, and spread it around the sides of the cake, too.
- Repeat two more times, using up all the ganache, until you've covered the top and sides of the cake with a smooth, shiny layer of ganache. As the ganache cools on the cake, it will firm up to a soft, fudge-like consistency.
- Fit a 12-inch disposable piping bag with a coupler and a small round piping tip (such as #3). Fill with the reserved buttercream.
- Pipe the icing in curly rows across the cake. Be sure to see the video in the recipe card to watch me decorate this cake!
Video
Notes
Store leftover cake in an airtight container at room temperature for up to three days.
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