Easy Chocolate Sheet Cake

May 14, 2017
8 Ratings
Photo by Posie Harwood
  • Makes one 9" x 13" cake
Author Notes

This simple, and delicious, chocolate cake recipe uses a neat one-bowl technique that makes it fast and no fuss to mix up at the merest hint of a chocolate craving. I've adapted it from an old Parkay margarine recipe. —Posie (Harwood) Brien

What You'll Need
  • For the cake
  • 1 cup water
  • 1/2 cup (8 tablespoons) unsalted butter
  • 1 1/2 ounces unsweetened chocolate
  • 2 cups (8 1/2 ounces) flour
  • 2 cups (14 ounces) granulated sugar
  • 2 eggs
  • 1/2 cup sour cream
  • 3/4 teaspoon espresso powder (optional, but enhances chocolate flavor)
  • 1 teaspoon baking soda
  • 1/2 teaspoon salt
  • For the frosting
  • 1 cup (16 tablespoons) unsalted butter
  • 6 tablespoons milk
  • 1 1/2 ounces unsweetened chocolate
  • 4 1/2 cups (About 16 ounces) sifted confectioners' sugar (start with less and add as needed)
  • 1 teaspoon vanilla
  1. Preheat the oven to 375 degrees F. Grease and flour a 9" x 13" pan.
  2. To make the cake: In a large saucepan, combine the water, butter, and chocolate. Bring to a boil, stirring occasionally, then remove from the heat.
  3. Add the flour, sugar, baking soda, salt, and espresso powder (if using) to the saucepan and whisk to combine.
  4. Add the eggs and sour cream and mix well. Pour the batter into the prepared pan and bake for 20-25 minutes, until the cake begins to pull away from the sides of the pan and springs back when touched lightly.
  5. To make the frosting: Add butter, milk, and chocolate to a saucepan and bring to a boil, stirring to melt the chocolate.
  6. Remove from the heat and add the sugar -- you may not need all the sugar so start with half or so and add to get to the right consistency. Beat with a handheld mixer (or transfer to the bowl of a stand mixer) until the frosting is smooth. If it is too liquidy, refrigerate the frosting for a bit and then try beating again. It'll thicken up as it cools and become nicely spreadable. Mix in the vanilla once the consistency is right.
  7. Spread the frosting over the cake, then cut into squares and serve.

See what other Food52ers are saying.

  • Barbara Sunday
    Barbara Sunday
  • Shelley Lawrence
    Shelley Lawrence
  • Pam Pershan Hochman
    Pam Pershan Hochman
  • Jesica
  • Posie (Harwood) Brien
    Posie (Harwood) Brien

20 Reviews

Barbara S. October 21, 2017
Is the 1.5 oz of chocolate hard chocolate or powdered chocolate? Thank you!
Barbara S. October 21, 2017
Is the 1.5 oz of chocolate hard chocolate or powdered chocolate? Thank you!
nanci June 25, 2017
Thought there was too much butter in frosting.
BTW-I added extra oz of chocolate in cake and frosting
Alexis June 6, 2017
Perfect! Never made it with less.
Shelley L. June 6, 2017
How did it come out?
Alexis June 5, 2017
I added twice the amount.
Shelley L. June 5, 2017
I made it Friday and thought the Sam thing. My people liked it but I might add more chocolate next time
Pam P. June 4, 2017
It seems like such a small amount of chocolate. Has anyone added more?
Shelley L. June 1, 2017
Do you take the cake out of the pan before frosting it?
Posie (. June 1, 2017
I don't -- it's simpler to just frost and serve from the pan!
Jesica June 1, 2017
Can it be done with regular cream instead of sour cream?
Posie (. June 1, 2017
Hm, not sure how that would affect the texture because it would make the batter much looser.
Jesica June 1, 2017
Then I will try to make my own sour cream and see how that works. Thanks for your reply!
Alexis May 29, 2017
While still recuperating from wrist surgery, I made this cake with my non-dominant hand and added chopped bittersweet chocolate pieces. Didn't frost yet still a huge success!
witloof May 28, 2017
Just to let you know that everyone loved this cake and I received many compliments and many requests for the recipe. I topped it with cream cheese frosting. It went so fast that I didn't actually get to taste it myself! I'm contemplating replacing half a cup of flour with a half cup of cocoa powder next time I make it.
Susanne May 26, 2017
There are 6 1/2 cups of sugar in this recipe? Am I reading that right?
Posie (. May 26, 2017
That includes the frosting! And it's 4 1/2 cups of sifted confectioners sugar in the frosting -- meaning sifted before measuring so pretty much a standard buttercream sugar amount :)
Susanne May 26, 2017
Thanks for the response! :-)
Therese May 31, 2017
For what it's worth, I cut back the sugar in the cake by 1/2 cup and it turned out fine.
witloof May 26, 2017
I have this in the oven now after looking for a recipe for a chocolate cake that would feed a crowd, transport easily, and come together quickly. Thanks!