Chocolate Birthday Sheet Cake With Strawberry Marshmallow Frosting

May 16, 2021
10 Ratings
Photo by Julia Gartland
  • Prep time 50 minutes
  • Cook time 30 minutes
  • Serves 16 to 20
Author Notes

This birthday cake basically tastes like the best chocolate strawberry Hostess Suzy-Q you ever did have—and I mean that in a good way. The cake is one-bowl and deeply chocolate-y. It is tender and moist and crumbles a bit as you take each bite. And the frosting is fluffy and fruity and light. The lemon juice in the frosting amps up the flavor of the strawberries, and a drop of red food coloring though optional, will brighten the color, if you so desire. This cake is unabashedly pink and it is one of my younger son’s absolute faves for his b-day. But I’m thinking it’d be just as lovely for Valentine’s Day. —Jessie Sheehan

What You'll Need
  • For the cake
  • 2 cups cake flour, sifted
  • 3/4 cup Dutch Process Cocoa Powder
  • 1 cup packed light brown sugar
  • 1 cup granulated sugar
  • 1 3/4 teaspoons baking powder
  • 1 teaspoon baking soda
  • 1 teaspoon table salt
  • 1 egg, room temperature
  • 2 egg yolks, room temperature, save the whites for the frosting
  • 1 tablespoon pure vanilla extract
  • 1/2 cup vegetable oil
  • 1 cup sour cream, room temperature
  • 1 cup boiling water
  • 1 tablespoon espresso powder
  • For the frosting
  • 1 cup sliced strawberries, plus more for decorating
  • 2 egg whites
  • 1/2 cup plus 2 tablespoons, granulated sugar
  • 1/4 teaspoon cream of tartar
  • 1/4 cup light corn syrup
  • 1/8 teaspoon table salt
  • 1 1/2 teaspoons lemon juice, or more to taste
  1. For the cake
  2. Preheat the oven to 350°F. Grease a 13-by-9-by-2-in pan with nonstick cooking spray or softened butter and line with parchment paper.
  3. Add the flour, cocoa powder, brown sugar, granulated sugar, baking powder, baking soda, and salt to the bowl of a stand mixer fitted with the paddle attachment; mix on low speed until well combined.
  4. In a small bowl, or in a large 4-cup liquid measuring cup (my preference), add the egg, egg yolks, vanilla, oil, and sour cream and whisk until combined. With the mixer on medium-low speed, slowly pour the wet ingredients into the dry ingredients. Beat until incorporated, scraping down the bowl with a rubber spatula as needed.
  5. In the same small bowl/measuring cup, no need to clean it, combine the boiling water and espresso powder and add to the batter in the mixer bowl. Mix again on medium speed for 30 seconds, until smooth, scraping the bowl with a rubber spatula as needed. The batter will be quite thin
  6. Pour the batter into the prepared pan and bake for 28 to 32 minutes, rotating at the halfway point. The cake is ready when a toothpick inserted in the middle comes out with a moist crumb or two. Let cool completely in the pan. Or let cool enough so you can comfortably handle it, and invert the cake on to a serving plate to continue cooling. If you would rather serve slices directly from the pan, let cool to room temp before frosting.
  1. For the frosting
  2. In a food processor fitted with the metal blade, or in a blender, process the berries until pureed. Place a sieve over a small bowl, pour the puree into the sieve, and using a rubber spatula, press the puree through the sieve to remove the seeds. Set aside.
  3. Add the egg whites, sugar, corn syrup, cream of tartar, and salt in the now-cleaned bowl of the stand mixer and nestle it in a saucepan of simmering water over medium-high heat. Donot allow the bottom of the bowl to touch the water. Whisk until the mixture is just warm to the touch. Remove the bowl from the heat, add the puree and transfer it to the stand mixer fitted with the whisk attachment. Mix on high speed until stiff and glossy, about 7 minutes. Add the lemon juice and whisk a final time to combine.
  4. Once the cake is cool, generously frost it and sprinkle the top with pink sanding sugar. The frosted cake is best served within a few hours with a few sliced strawberries on each plate - or, a scoop of strawberry ice cream - I mean this is a birthday cake, after all.

See what other Food52ers are saying.

  • FrugalCat
  • Kristin
  • Justine Lee
    Justine Lee
  • Sabine Gagnon
    Sabine Gagnon
  • Jessie Sheehan
    Jessie Sheehan
Bio: Jessie Sheehan is the author of The Vintage Baker and Icebox Cakes. Her new easy-peasy baking book, Snackable Bakes, hits shelves in spring 2022. She contributes to the Washington Post, Bon Appétit, Food Network, and the Kitchn, among others.

13 Reviews

cattydids July 5, 2022
I substituted 1/2 cup of oil with softened for the oil and 1 cup of the sour cream with buttermilk. I also added 4 tablespoons of malted milk powder with the espresso powder and hot water.
I creamed the butter, sugars, vanilla first. Then added the eggs and buttermilk. Then I alternated adding the mixed dry ingredients and espresso, malted milk powder and water mixture. It turned out really well. Such a light and moist cake with tons of flavor!
Jessie S. July 6, 2022
Glad to hear it! Sounds delicious.
FrugalCat April 22, 2022
The cake was excellent. I cooked it in a silicone muffin pan. The frosting seemed a little too ambitious, so I just put whipped cream on top of each one.
Jessie S. April 22, 2022
glad you liked the cake! and whipped cream on top sounds yum.
Kristin August 22, 2021
This baked up wonderfully! And it does indeed resemble a Hostess treat, especially the cake's crumb but also the pink marshmallow frosting. One thing to note is if you defer applying the frosting, you might consider refrigerating it. I left it out on the counter and it changed consistency a bit - still tasty very yummy but loss some of its density. Also, I let my berries macerate a bit with approximately 1 T of sugar to try to fend off any bitterness since our local strawberry season is long gone in Oregon and was working with store-bought organics from Costco. But yes I would definitely to make this again!
Jessie S. August 22, 2021
thank you for letting me know that you made this!! and so happy you liked!! and yes: i should be a little clearer about how important it is to use the frosting right away. seven minute frostings don't really keep all that well - so they are best when applied ASAP.
Justine L. May 16, 2021
Just adore this sheet cake recipe!! I made it for my friend who is gluten-free so I substituted the cake flour for Gluten Free Measure-for-Measure flour from King Arthur. Still, it baked into a gorgeous moist and tender chocolate cake! Subbed bloobs instead of strawberries bc that was all I had and it yielded a gentle periwinkle fluffy frosting. This is the perfect celebration cake!
Sabine G. May 2, 2021
Made this exactly as written and it was excellent! I had some super sweet strawberries- they were incredible in this mallow frosting! My sweet girl turned 7 and she loved this cake!
Jessie S. May 3, 2021
This makes me so happy!! So glad it was a success and happy bday!
Lisa May 27, 2020
I baked this for my son's birthday a couple of weeks ago and it was delicious! The cake was perfect but my strawberries were on the tart/unripe side so the frosting didn't have as much strawberry flavor as I would have liked like so I will make this again with more flavorful berries. I will definitely be making this again and again. Thank you Jessie for a great recipe!
Jessie S. May 27, 2020
Yay! Really glad you made this and glad you enjoyed. Sorry about the strawberries. That’s a bummer, but so pleased you’ll make the cake again anyway!
Marissa March 17, 2019
So easy and yummy! I saw this cake on Instagram a few weeks ago and just now got the chance to try it. The cake tastes closer to dark chocolate than milk chocolate, which I like. The frosting is very light and fluffy. My strawberries were more on the sour side so I didn’t need to add the lemon juice. I would defiantly make this cake again.
Jessie S. April 23, 2019
yay! so happy to read this and so sorry i missed it when you first wrote it. XO