Marbled Snack Cake with Chocolate Swirled Frosting

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A moist vanilla sponge ribboned with chocolate cake and topped with swirls of smooth buttercream—aside from being delicious, this cake is so simple that it’s the perfect dessert or indulgent snack!

What is a Snack Cake?

Typically, a snack cake is just a sheet cake with little to no frosting. They’re often already cut into squares, making them easy to pick up and eat with one hand (hence the “snack” moniker). In my opinion, any cake can be a snack cake if you’re willing enough, but I can’t argue that recipes like this make the cutest and most convenient cake slices!

I adapted this recipe from Claire Saffitz’s marbled sheet cake (the link to her cookbook is in the recipe)! This cake uses a mayonnaise and oil-based batter to keep the texture plush and soft. Half of the batter has cocoa added for the chocolate layers, then you simply swirl the two together to create a “marbled” effect.

Ingredients You’ll Need

Most of the things you’ll need for this recipe are pantry staples for baking. Here’s what you’ll need:

  • All-purpose flour.
  • Baking powder.
  • Baking soda.
  • Kosher salt.
  • Unsweetened cocoa powder.
  • Coffee. You won’t be able to taste it! Coffee is used to enhance the chocolate flavor of the cake and to add more depth.
  • Granulated sugar.
  • Eggs.
  • Mayonnaise. Yes, you heard me right—mayonnaise. Not only does it add a richer flavor, but it keeps the cake nice and moist.
  • Vegetable oil.
  • Vanilla extract.
  • Buttermilk.
  • Unsalted butter.
  • Powdered sugar.
  • Milk.

Marbled Cake Tips and Tricks

  1. Do not overmix the batter. Whenever you overmix wheat flour, you create gluten. This is great for recipes like bread that need a lot of structure and strength, but not so much for soft and delicate cakes. To avoid a dense and rubbery texture, only mix the batter until it’s just combined!
  2. Have all ingredients at room temperature. Cakes bake best with room temperature ingredients—that way, the batter won’t split and everything will seamlessly incorporate.
  3. Use a cookie scoop to layer the cake. To get the marbled effect, you need to alternate pouring vanilla and chocolate cake batters into a baking pan. I prefer to do this with a cookie scoop, since I have more control with how much batter I pour in, but you can always do this with a spoon or by simply pouring both batters at the same time.

Hope you like this recipe! Leave any questions you have in the comments and be sure to give it a try!

Marbled Snack Cake with Chocolate Swirl Frosting

A moist vanilla sponge ribboned with chocolate cake and topped with swirls of smooth buttercream—aside from being delicious, this cake is so simple that it's the perfect dessert or indulgent snack!
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Course: Desserts
Keyword: cake, chocolate, vanilla
Total Time: 2 hours
Servings: 9 slices
Author: Adapted from Claire Saffitz

Ingredients

For the cake

  • 1½ cups all-purpose flour
  • 1 teaspoon baking powder
  • ½ teaspoon baking soda
  • ½ teaspoon kosher salt
  • 2 tablespoons unsweetened cocoa powder
  • 3 tablespoons brewed coffee
  • ¾ cup plus 3 tablespoons granulated sugar
  • 2 eggs, at room temperature
  • ½ cup good-quality mayonnaise
  • ¼ cup vegetable oil
  • 2 teaspoons vanilla extract
  • ½ cup plus 2 tablespoons buttermilk, at room temperature

For the frosting

  • ½ cup unsalted butter, softened
  • 1 cup powdered sugar, sifted
  • 1 teaspoon vanilla extract
  • A pinch of salt
  • 2 tablespoons unsweetened cocoa powder, sifted
  • 1-2 tablespoons milk, if needed

Instructions

  • Preheat the oven to 325℉. Spray an 8×8 inch pan with baking spray and line with parchment paper.
  • In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
  • To another bowl, whisk together the cocoa powder, coffee, and 1 tablespoon of sugar until smooth. Set aside.
  • Using a hand mixer, combine the 2 eggs and the remaining sugar (¾ cup plus 2 tablespoons) in a large bowl. Whip the mixture on medium speed until thick, pale, and voluminous (about 3 minutes).
  • Whisking continuously, gradually add the mayonnaise to the whipped eggs a few tablespoons at a time until fully incorporated. Gradually stream in the vegetable oil until well combined and smooth, then add the vanilla extract.
  • Reduce the speed of the hand mixer to low and add ⅓ of the dry ingredients, mixing until just combined. Stream in ½ of the buttermilk. Add the remaining dry ingredients in two additions, alternating with the buttermilk and being careful not to overmix.
  • Pour half of the batter into the bowl of the cocoa mixture. Gently beat with a hand mixer on low speed or fold the mixture until the chocolate batter is streak free.
  • With a cookie scoop, pour the cake batters into the prepared pan, alternating between the vanilla and chocolate to layer them on top of one another. Once all the batter is in the pan, use a wooden skewer or paring knife to swirl the mixture in figure eight motions.
  • Bake the cake for 35-45 minutes, or until the cake is lightly golden on top and a toothpick inserted into the center comes out clean. Allow the cake to cool fully before decorating.
  • To make the frosting, beat the butter in a medium bowl until smooth. Add the powdered sugar and whisk until light and fluffy, then add the vanilla extract and salt.
  • Divide the frosting into two bowls. Add the cocoa powder to one half of the frosting, mixing until evenly distributed. Adjust the consistency if needed, adding milk if the icing is too thick or powdered sugar if it is too thin.
  • Spread the frosting onto the cooled cake in swirling motions, alternating with the chocolate and vanilla, until the entire cake is coated. Using the parchment paper, gently lift the cake from the baking pan and slice into 9 pieces. Serve immediately or store at room temperature for 2-3 days.