Double Chocolate Zucchini Cake is fudgy and moist, filled with cocoa, studded with dark chocolate chips and topped with a creamy chocolate avocado frosting. It tastes a little indulgent yet it’s filled with wholesome ingredients. Your family will never know they’re eating their veggies!
If you love this chocolate cake with zucchini, you’ll also love these chocolate zucchini cupcakes! (These almond flour zucchini muffins are definitely worth a try too!)
*This post was originally published in May 2017 and has been updated with new text and photos and a few tweaks to the recipe.
When I first started Crumb Top Baking this was definitely my most popular recipe, and it’s still one of my most requested desserts whenever I’m asked to make one.
So, when zucchini season rolls around, this chocolate zucchini cake with apple sauce tops my list to make!
Why you’ll love this recipe
- It’s a double chocolate zucchini cake with cocoa and dark chocolate chips. So it tastes like a rich and decadent chocolate cake, but the ingredient list is far from indulgent.
- It’s not an overly sweet cake, containing very little refined sugar. It’s sweetened with honey, coconut sugar and some dark chocolate chips. It’s loaded with cocoa flavor, which I think makes up for the lack of sweetness.
- There isn’t any butter or a large quantity of oil in this recipe. The fats come from the flax meal and extra virgin olive oil.
- The cake is simple to make (even though the ingredient list is long) and stores well in the refrigerator, so it can easily be made in advance.
Details on a few ingredients
Zucchini – The recipe calls for one cup of grated zucchini, which may seem like a lot, but it has a mild flavor so it doesn’t affect the taste of the cake. It adds moisture and texture, as well as some added nutrition such as fibre.
Apple sauce – Unsweetened apple sauce also adds moisture and extra fibre to this cake. It’s often used as a replacement for butter in baking.
Whole wheat flour – This is my preferred flour to keep this cake on the healthier side. It’s also more absorbent than white flour, so it works well with all the moisture in this cake.
Flax meal – Ground flax seed is concentrated with oil so a tablespoon is used to compensate for the small amount of oil added to the cake.
How to make chocolate cake with zucchini
Step 1: In a medium-sized bowl, whisk or sift together your dry ingredients.
Step 2: In a separate large bowl, whisk together the egg with the other wet ingredients.
Step 3: Add the dry ingredients to the wet ingredients and stir until combined. Gently mix in the zucchini and chocolate chips. Don’t over mix.
Step 4: Spread the batter out into an 8-inch square pan that has been greased and lined with parchment paper. Bake for 25-27 minutes. Cool on a wire rack.
How to make chocolate avocado frosting
Step 5: Add ripe avocado, cocoa, maple syrup and nut milk to a medium sized bowl or blender and beat with an electric mixer or blend on high until smooth and creamy. (To minimize the cocoa dust, you can add the cocoa in small portions and beat after each addition).
Step 6: Spread the frosting over the cooled cake and cut into squares.
Storage instructions
If your zucchini cake is unfrosted, you can wrap it in plastic wrap or store it in an airtight container at room temperature. It should last for 2-3 days.
If the cake is frosted, store it in an airtight container in the fridge and enjoy within 4-5 days.
Frequently asked questions
No need to peel. The skin is very thin so while you will see flecks of green in the cake, it really isn’t noticeable otherwise. Just be sure to choose zucchini that are free of dents or scratches on the skin, and wash well before grating.
While some recipes call for draining or pressing the water out of zucchini before adding it to cake batter, this recipe accounts for the added moisture so there’s no need to do that. In fact, if you do it, the cake may be too dry.
The unfrosted cake can be frozen. Just wrap it tightly in plastic wrap and place in an airtight container. Store in the freezer for up to 3 months. Let it defrost in the plastic wrap at room temperature before frosting. I don’t recommend freezing the frosted cake as I’m not sure how the avocado frosting will hold up once frozen and defrosted.
Recipe tips and substitutions
- I recommend shredding your zucchini using the larger shredding holes of a box grater (cheese grater). Don’t grate it with the smaller holes as the zucchini will be too finely shredded and will release too much moisture into the cake.
- I used dutch-processed cocoa in the cake recipe. I haven’t tested the cake with natural cocoa. The frosting, on the other hand, works with both kinds of cocoa.
- You can make this recipe in a 9×5 inch loaf pan. Just increase the baking time by 7-10 minutes, or until a toothpick inserted in the middle comes out clean.
- While I make the chocolate avocado frosting all the time with my handheld electric mixer, I find blending it in the smoothie cup that came with my blender results in the creamiest and smoothest frosting. It’s also a little less messy.
- This zucchini cake with chocolate chips isn’t overly sweet, but if you’d like to make it sweeter, try adding some sweetened coconut flakes or chocolate shavings to the top of the frosting.
More chocolate desserts
- Chocolate Peanut Butter Nice Cream Cake
- Easy Vegan Chocolate Sheet Cake with Peanut Butter Frosting
- Peanut Butter Brownie Ice Cream Sandwiches
If you make this zucchini cake recipe, I’d love to hear what you think in the comments below.
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Double Chocolate Zucchini Cake
- Prep Time: 20 minutes
- Cook Time: 25 minutes
- Total Time: 3 hours
- Yield: 16 squares
- Category: Dessert
- Method: Bake
- Cuisine: American
Description
Chocolate Zucchini Cake is fudgy and moist, studded with dark chocolate chips and topped with a creamy chocolate avocado frosting. It tastes a little indulgent yet it’s filled with wholesome ingredients. Your family will never know they’re eating their veggies!
Ingredients
For the cake:
- 1 cup whole wheat flour
- 1/3 cup unsweetened cocoa (dutch-processed)
- 1/4 cup coconut sugar
- 1 tablespoon flax meal
- 1/2 teaspoon baking soda
- 1/2 teaspoon baking powder
- 1/2 teaspoon kosher salt
- 1 large egg
- 1/3 cup unsweetened apple sauce
- 1/4 cup extra virgin olive oil
- 1/4 cup honey
- 1/4 cup unsweetened nut milk
- 1 teaspoon vanilla extract
- 1 cup grated zucchini
- 2 tablespoons dairy-free dark chocolate chips
For the frosting:
- 1 ripe large avocado (or 2 small)
- 1/3 cup unsweetened cocoa
- 1/4 cup maple syrup
- 2 tablespoons nut milk
Instructions
- Pre-heat oven to 350F. Grease an 8-inch square pan and line it with parchment paper.
- In a medium-sized bowl, whisk or sift together the flour, cocoa, coconut sugar, flax meal, baking soda, baking powder and salt.
- In a large bowl, whisk together the egg, apple sauce, oil, honey, milk and vanilla.
- Add the dry ingredients to the wet mixture and stir until combined. Gently mix in the zucchini and chocolate chips. Don’t over mix.
- Spread the batter out evenly in the prepared pan and bake for 25-27 minutes, or until a tooth pick inserted in the middle comes out clean.
- Let cool completely in the pan on a wire rack.
- To make the frosting, add the avocado, cocoa, maple syrup and milk to a mixing bowl or blender and beat with an electric mixer or blend on high until smooth and creamy.
- Use the edges of the parchment paper to lift the cooled cake out of the pan. Spread the frosting evenly over the top of the cake.
- Cut into 16 squares and store in an airtight container in the refrigerator. Enjoy within 4-5 days.
Notes
- Make sure to shred the zucchini using the larger shredding holes of a box/cheese grater. Don’t grate it with the smaller holes as the zucchini will be too finely shredded and will release too much moisture into the cake.
- There is no need to squeeze the water out of the grated zucchini before adding it to the cake batter. The recipe accounts for this added moisture.
- While I make the frosting all the time with my handheld electric mixer, I find blending it in the smoothie cup that came with my blender results in the creamiest and smoothest frosting. It’s also a little less messy.
- If you use an electric mixer, you may want to add the cocoa in small portions and beat after each addition. This will help minimize the cocoa dust.
- The total time in the recipe includes time for the cake to cool.
- Be sure to check out the tips and substitutions section above the recipe card for more detailed advice and suggestions for making this recipe.
Thank you darling for the recipe. I’m using this as a reference for my son’s birthday on sunday tomorrow xD. He’s turning 5 yo btw.
That’s great! I hope your son enjoys the cake and has a happy birthday!
This looks fabulous Leanne! I really need to try that avocado frosting!!
Thanks Tasia!
I want to grab a slice through my screen Leanne! Looks delicious!
Thanks Mary Ann!
Love this cake, Leanne! It’s one of my favorite ways of using up my zucchini stash! That frosting is so dreamy!
Thanks so much Kelly!
A healthy cake never looked (and I can see that) tasted so delicious, and most importantly, so decadent! I love the the moist texture of the cake and this irresistibly silky avocado frosting. Good job!
Thanks so much Ben! I could eat the frosting on its own!
Just beautiful and I’m always on board when chocolate is involved 🙂 That frosting looks fabulously creamy!
Thanks Jennifer!
I’m a little sad that I didn’t plant any zucchini in my garden — this looks cake looks incredible! And so super healthy! I’m gonna have to bookmark this for my kids when they ask me for a decadent dessert 😛
Thanks Michelle! I wish I had a garden! Thank goodness for farmers’ markets!
Chocolate and avocado work so well together, so I am really loving the sound of this icing!
Thanks Alex!
I made this recipe yesterday and I LOVE IT! I did make a few substitutions for things I didn’t have, plus I’m not super worried about it being a “healthy” cake. I mean, it’s cake. I used all purpose white flour instead of wheat, I used plain white sugar instead of coconut (plus I added an extra ¼ cup and didn’t add honey), I used regular 2% milk instead of almond milk, and I left out the flax meal and dark chocolate chips entirely. It turned out so delicious, even my unbelievably picky husband loves it! This one is definitely going in the recipe book, thank you!!
That’s great. I’m glad those substitutions worked out for you. Thanks for letting me know Rebecca!
Di I need to squeeze and drain the water from the grated zucchini? Or use it as is? Thanks 🙂
Hi Nina. No need to drain the grated zucchini. Just add it to the cake mix as is. Thanks!
Made it gluten free and in a round pan with some sprinkles (hubby is very health conscious and wanted to have a birthday morning cake with the kids). Everyone loved it! Like a super healthy brownie and delicious! And no I didn’t mention the zucchini or avocado to the kids…Thank you 🙂
That’s awesome Nina! Thanks for following up to let me know. I’m so glad you and your family liked it! You seriously just made my day! And good call on not mentioning the zucchini or avocado. I usually don’t mention it either 😉
This cake looks so gooey and chocolatey!! And that icing!,
Thanks Lisa! The zucchini keeps this cake super moist, and all the cocoa and chocolate chips keep it pretty chocolatey! The avocado icing is one of my go-to dairy-free frostings!
This cake has everything I have been waiting to try out for so long. I am most definitely going to try this cake and that avocado frosting out. Thanks for the reminder with this post. All that brown and green together looks so gorgeous btw. 🙂
Thanks Neha! This is one of my fave dessert recipes! I hope you like it. Be sure to let me know how it goes!
Delicious – I have sampled it on a couple of occasions!
Great. I’m glad you enjoyed! Thanks for being a repeat taste tester!