Recipe: Sourdough Chocolate Cake with Coffee Icing

I maintain a sourdough starter. Mostly because I keep telling myself that I’m going to start regularly making sourdough bread (yeah…still working up to that). Also, by “maintain,” I mean, “store it in the refrigerator and ignore it for weeks and then work feverishly to revive it before it dies.”

But because it exists, and even though I’m not the most committed sourdough tender, I’m always on the lookout for recipes that can be made with the starter — recipes other than the standard “Rustic Sourdough Loaf” or “Classic Sourdough Bread.” So when a recipe for Sourdough Chocolate Cake came across my radar a few weeks ago, I was instantly intrigued. Chocolate? Cake? With sourdough starter?  I would have to give it a try.

And so I did. If the reactions of my husband and 11-year-old son are any indication, it was a hit, and truly a worthwhile use of the often-neglected but never-forgotten sourdough that humbly occupies a corner in the back of the fridge. I have to admit, I liked it too. (But then again, I’m pretty easy to please when it comes to chocolate cake.)

I adjusted the original recipe a bit — mostly to lighten up the icing/frosting a little, but also to lower the amount of espresso powder (the original recipe called for what I knew would be too much for my son — both taste-wise and I-don’t-want-my-kid-to-get-too-wired-wise).

The result: a unique twist on a chocolate cake that I would gladly make again. Chocolatey and moist, yes. With a good dose of coffee flavor (though you could leave out the espresso powder and use a different icing if coffee is not your thing). The sourdough creates a light, fluffy texture and imparts just a hint of tang and…”different.” Different-good, not different-bad.

Yes, it’s a little more time-intensive than a standard cake, because you have to prep and babysit the sourdough starter a bit. But on a quiet Saturday? Totally doable.

A few notes before making this Sourdough Chocolate Cake

1. If, like me, you keep your sourdough starter in the back of the fridge, you will want to prepare for this recipe at least a day in advance by reviving/feeding your starter and getting it nice and “happy.” For me, that meant moving it from fridge to counter on the day before I planned to bake, and feeding it twice (12 hours apart). I then fed it once more on the morning of baking, followed by giving it a couple hours to get nice and bubbly before moving on to the recipe.
2. The batter is definitely thicker than a normal cake batter, but don’t worry — that’s normal!
3. The icing is intended to be “pourable,” so don’t panic if it’s a little runny after you’ve mixed it. However, if you think it is too runny to use, just add more confectioners’ sugar, a spoonful at a time, to reach the desired consistency. We found the topping to be more of an icing than a frosting, if that makes sense. (Also, this makes quite a bit of icing — you may find you don’t need all of it. In my case, I just handed to bowl to my husband and he made the rest magically “disappear.”)
4. The icing has a strong coffee flavor, which we loved (even the 11-year-old), but not everyone will feel the same. Next time I make this cake, I plan to leave the espresso powder out of the cake, and substitute a peanut butter frosting. I have a feeling that will be a hit as well.

This recipe has been adapted from the original, which can be found at King Arthur Flour.

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Sourdough Chocolate Cake with Coffee Icing

Course Dessert

Servings 18

Ingredients

Cake Ingredients

• 1 cup sourdough starter fed & bubbly
• 1 cup 2% milk
• 2 cups unbleached, all-purpose flour
• 1 1/2 cups granulated sugar
• 1 cup vegetable oil
• 2 teaspoons vanilla extract
• 1 teaspoon salt
• 1 1/2 teaspoons baking soda
• 3/4 cup unsweetened cocoa (NOT Dutch process)
• 1/2 teaspoon espresso powder
• 2 large eggs

Icing Ingredients

• 5 cups confectioners' sugar
• 10 tablespoons butter
• 1/3 cup plain, nonfat yogurt
• 2 1/2 teaspoons espresso powder
• 2 1/2 teaspoons hot water
• 1/3 cup semisweet chocolate chips
• 1 tablespoon milk
• 1 tablespoon light corn syrup

Instructions

The Day Before

1. If your sourdough starter lives in the refrigerator, start prepping the day before to get it "happy" and bubbly. See notes in blog post for more info.

Cake Instructions

1. Stir together fed sourdough starter, milk, and flour in a medium bowl. Cover with plastic wrap and allow to sit at room temperature for 2-3 hours. It will probably not bubble, but will smooth out and may expand a bit.

2. Preheat oven to 350 degrees and grease a 9x13 baking pan.

3. In a large mixing bowl, combine the sugar, oil, vanilla, salt, baking soda, cocoa, and espresso powder. Mix on medium with your stand or hand mixer until well combined.

4. Beat in eggs, one at a time, allowing the first to become completely incorporated before adding the second.

5. Add the starter/flour/milk mixture to the bowl and combine, using the "stir" or low setting on your mixer. Gently combine the two mixtures until smooth and cohesive. (It will take a little while for the starter mixture to become fully blended with the chocolate mixture.)

6. Pour batter into the 9x13 pan.

7. Bake for 30-40 minutes, or until a toothpick inserted in the center comes out clean. The edges of the cake may be just starting to pull away from the pan.

8. Remove from oven, and set on cooling rack to begin cooling while you prepare the icing.

Icing Instructions

1. Sift confectioners' sugar into a large bowl.

2. Place a small sauce pan on your stove over medium heat, and add butter and yogurt. Heat until butter is melted.

3. Dissolve espresso powder in the hot water in a small bowl or mug, then add to sauce pan.

4. Bring mixture just to a boil, then immediately pour over confectioners' sugar in the large bowl.

5. Beat until smooth.

6. Pour icing over cake. 

7. In a small microwave-safe bowl, place chocolate chips, 1 Tbsp milk, and light corn syrup. Microwave 10 seconds at a time, until chips soften. Stir until smooth.

8. Drizzle chocolate over coffee icing with a spoon, or use a plastic bag with the corner snipped off.

Recipe Notes

We found that chilling the cake in the refrigerator after adding the icing helped everything to set up nicely.