Tasty Chocolate Zucchini Cake

If you ask me, chocolate zucchini cake is one of the best ways to use up summer garden zucchini.

This moist chocolate cake hides shredded zucchini inside, making it a sneaky way to add vegetables to dessert. Rich cocoa and melted chocolate chips pair with the mild zucchini that keeps everything tender.

It’s loaded with brown sugar for deep sweetness and a touch of espresso powder to bring out the chocolate flavor. Sour cream and butter help create a soft crumb that stays fresh for days.

It’s a family-friendly dessert that feels indulgent but uses up all that extra zucchini sitting on your counter.

What Kind of Zucchini Should I Use?

For this chocolate cake, you’ll want to use medium-sized zucchini rather than those giant ones you sometimes see at the farmers market. The smaller to medium zucchini are more tender and have fewer seeds, which means better texture in your cake. You don’t need to peel the zucchini before shredding it – the skin actually disappears into the batter and adds extra moisture. After you shred it, there’s no need to squeeze out the excess water like you might for other recipes, since that moisture is exactly what keeps this cake so soft and tender.

Options for Substitutions

This chocolate zucchini cake is pretty forgiving when it comes to swaps:

• All-purpose flour: You can use a 1:1 gluten-free flour blend if needed. The texture might be slightly different, but it’ll still taste great.
• Sour cream: Plain whole milk yogurt works perfectly here, or you can use Greek yogurt thinned with a tablespoon of milk. Just make sure it’s at room temperature so it mixes smoothly.
• Vegetable oil: Canola oil, melted coconut oil, or even more melted butter can replace the vegetable oil without any issues.
• Light brown sugar: Regular granulated sugar works fine, though you’ll lose a bit of that molasses flavor. You can also use dark brown sugar for a deeper taste.
• Zucchini: Yellow squash makes a great substitute and works exactly the same way. Just shred it and squeeze out any excess moisture before adding it to the batter.
• Semisweet chocolate chips: Dark chocolate chips, milk chocolate chips, or even chopped chocolate bars all work here. Pick whatever suits your sweetness preference.
• Unsalted butter: If you only have salted butter, just reduce the added salt to 1/2 teaspoon to balance things out.

Watch Out for These Mistakes While Baking

The biggest mistake when making chocolate zucchini cake is not squeezing out enough moisture from the shredded zucchini, which can leave you with a dense, wet cake that takes forever to bake through – use a clean kitchen towel or paper towels to wring out as much liquid as possible.

Another common error is measuring cocoa powder incorrectly by scooping it directly from the container, which packs it down and gives you too much, resulting in a dry, bitter cake – always spoon it into your measuring cup and level it off.

Don’t skip bringing your eggs and sour cream to room temperature, as cold ingredients won’t mix properly with the melted butter and can create a lumpy batter.

Finally, resist the urge to open the oven door during the first 25 minutes of baking, since the temperature drop can cause the cake to sink in the middle and bake unevenly.

What to Serve With Chocolate Zucchini Cake?

This cake is rich and moist enough to stand on its own, but a scoop of vanilla ice cream or a dollop of whipped cream takes it to the next level. I love serving it with a hot cup of coffee or cold glass of milk, especially when it’s still slightly warm from the oven. If you’re looking to dress it up for company, try adding some fresh berries on the side – raspberries or strawberries work great with the chocolate. For a casual afternoon snack, just slice it up and enjoy it as-is, since the chocolate chips and light glaze give it plenty of sweetness without needing anything extra.

Storage Instructions

Store: This cake stays moist for days thanks to the zucchini! Keep it covered with plastic wrap or in an airtight container at room temperature for up to 3 days. If your kitchen is really warm, you can store it in the fridge for up to 5 days, though I think it tastes best at room temperature.

Freeze: Chocolate zucchini cake freezes really well, either as a whole cake or in individual slices. Wrap it tightly in plastic wrap, then in foil, and freeze for up to 3 months. I like to slice it first so I can grab just one piece whenever I’m craving something sweet.

Thaw: Let frozen slices sit at room temperature for about 30 minutes, or thaw the whole cake in the fridge overnight. The texture comes back perfectly, and honestly, sometimes I think it tastes even better the next day once all the flavors have had time to meld together.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2800-3000
• Protein: 35-45 g
• Fat: 130-145 g
• Carbohydrates: 370-395 g

Ingredients

For the cake:

• 1 1/8 cups flour (I always use King Arthur all-purpose flour)
• 2/3 cup cocoa
• 1 cup brown sugar
• 1 tsp salt
• 1 tsp baking soda
• 4 tbsp butter (I like Kerrygold unsalted butter for this)
• 1/4 cup oil
• 1/2 cup sour cream (room temperature, about 70°F)
• 2 eggs
• 1 egg yolk
• 1 tablespoon vanilla
• 1 cup zucchini (finely shredded and squeezed of excess moisture)
• 1 cup chocolate chips (I prefer Ghirardelli semi-sweet)
• 1/2 teaspoon espresso powder

For the glaze:

• 1/2 cup sugar
• 1 1/2 tablespoons milk
• 1 pinch salt

Step 1: Prepare the Dry Ingredients and Pan

• 1 1/8 cups flour
• 2/3 cup cocoa
• 1 cup brown sugar
• 1 tsp salt
• 1 tsp baking soda
• 1/2 teaspoon espresso powder

Preheat your oven to 350°F and grease a 9×13 inch baking dish or similar size cake pan.

While the oven heats, whisk together the flour, cocoa powder, brown sugar, salt, baking soda, and espresso powder in a large bowl.

The espresso powder won’t make the cake taste like coffee—it intensifies the chocolate flavor by enhancing the cocoa’s natural depth.

Set this dry mixture aside.

Step 2: Prepare the Wet Ingredients and Zucchini

• 4 tbsp butter
• 1/4 cup oil
• 1/2 cup sour cream
• 2 eggs
• 1 egg yolk
• 1 tablespoon vanilla
• 1 cup zucchini

While the oven preheats, prepare your zucchini by finely shredding it and squeezing out excess moisture using a clean kitchen towel—this step is crucial because too much water will make the cake dense and soggy.

In a separate bowl, whisk together the softened butter, oil, room-temperature sour cream, eggs, egg yolk, and vanilla until well combined and smooth.

I like to let the sour cream sit on the counter for a few minutes before using it because the warmth helps it blend more smoothly with the other wet ingredients.

Step 3: Combine and Finish the Batter

• dry ingredient mixture from Step 1
• wet ingredient mixture from Step 2
• 1 cup chocolate chips

Pour the wet ingredient mixture from Step 2 into the dry mixture from Step 1, then stir until just combined—don’t overmix, as this can develop too much gluten and result in a tough cake.

Fold in the prepared zucchini and chocolate chips gently until evenly distributed throughout the batter.

I prefer Ghirardelli semi-sweet chips because they hold their shape well and don’t overpower the chocolate flavor of the cake itself.

Step 4: Bake the Cake

• batter from Step 3

Pour the batter into your prepared pan and spread it evenly.

Bake for 30-35 minutes, until a toothpick inserted into the center comes out with just a few moist crumbs—the cake will continue to set as it cools, so don’t overbake.

The cake should spring back slightly when you touch the center.

Step 5: Make and Apply the Glaze

• 1/2 cup sugar
• 1 1/2 tablespoons milk
• 1 pinch salt

While the cake bakes, prepare the simple glaze by whisking together the sugar, milk, and a pinch of salt in a small bowl until smooth.

Once the cake comes out of the oven and is still warm but cool enough to touch (about 5 minutes), pour the glaze evenly over the entire surface.

The warmth of the cake will help the glaze set and absorb slightly into the crumb.

Step 6: Cool and Serve

Allow the cake to cool completely in the pan before slicing and serving.

This cake actually tastes even better the next day once the flavors have had time to meld together, so feel free to make it ahead.