Chocolate Zucchini Sheet Cake with Cream Cheese Frosting

This chocolate zucchini sheet cake is my Memere’s recipe, a moist chocolate chip zucchini cake baked in one 9×13 pan and covered edge to edge in cream cheese frosting. Two full cups of zucchini go in, and nobody ever finds them.

My French grandma, Memere, has been making this cake for as long as I can remember, and at last count at least 19 people in my extended family will fight you for a corner piece. It’s the cake that shows up every time someone’s garden goes overboard and there’s zucchini on every counter.

Chocolate zucchini sheet cake is a moist chocolate cake made with shredded zucchini, cocoa, butter, oil, and chocolate chips, baked in a 9×13 pan and topped with cream cheese frosting. The zucchini melts into the crumb for moisture, and you cannot taste it. Not even a little.

I kept her recipe exactly the way she makes it, real butter, real cream cheese, all of it, because some things you just don’t mess with.

Chocolate Zucchini Sheet Cake Ingredients

For the cake

• Shredded zucchini: the reason this cake stays so soft. It goes into the batter raw, straight off the grater.
• Milk and white vinegar: stirred together, they thicken into a quick homemade buttermilk for a tender crumb. Apple cider vinegar or lemon juice work too.
• Butter and olive oil: you need both. Butter brings the flavor, and oil stays liquid at room temperature, so every bite reads as moist.
• Sugar, eggs, and vanilla: the base that holds it all together.
• All-purpose flour and cocoa powder: sift both so you don’t end up with bitter cocoa lumps.
• Baking soda and baking powder: the baking soda reacts with the vinegar milk for lift.
• Cinnamon: a tiny bit warms up the chocolate without making it taste like spice cake.
• Chocolate chips: folded right into the batter, so you get melty pockets in every square.

For the cream cheese frosting

• Block cream cheese and butter: softened, so they beat together completely smooth.
• Vanilla and powdered sugar: for a thick, fluffy frosting with enough to go right to the edges.

Do You Peel or Squeeze the Zucchini?

No and no. The skin is thin and disappears into the dark batter, and the water inside the zucchini is exactly what makes this cake so moist. Squeeze it out and you’re left with a drier cake.

How to Make Chocolate Zucchini Sheet Cake

1. Preheat your oven to 350°F and grease a 9×13 pan. Line it with parchment if you want to lift the whole cake out later.
2. Stir the milk and vinegar together in a small bowl and let it sit while you mix everything else.
3. Cream the butter and oil together in a large bowl.
4. Beat in the sugar, then the eggs one at a time, then the vanilla and the thickened milk.
5. Whisk the flour, cocoa, baking powder, baking soda, and cinnamon in a separate bowl.
6. Add the dry ingredients to the wet and mix until just combined.
7. Fold in the zucchini and chocolate chips. The batter will be thick, that’s how it should look.
8. Spread it into the pan and bake for 33 to 36 minutes, until a toothpick in the center comes out clean.
9. Cool the cake completely in the pan on a wire rack. Frost it warm and the frosting slides right off.

Make the Cream Cheese Frosting

1. Beat the cream cheese and butter with an electric mixer until smooth.
2. Add the vanilla and powdered sugar and beat until fluffy.
3. Spread it over the cooled cake, all the way to the edges.

Tips and Swaps

• Toothpick hit a chocolate chip? Melted chocolate fools the test every time. Poke a second spot before you add more minutes.
• Want chocolate frosting? Beat a little cocoa powder into the cream cheese frosting. The exact amount is in the recipe card notes.
• Deeper chocolate flavor: add a pinch of espresso powder to the dry ingredients. It won’t taste like coffee, it makes the cocoa taste more like itself.

Can I Make It Dairy-Free?

Yes. I’ve made this with vegan butter, almond milk, and vegan cream cheese and it turned out SO good. The classic version stays on the recipe card because that’s how Memere makes it.

Can I Use Less Sugar?

You can pull some back, or swap part of it for coconut sugar or brown sugar. Start small, because cutting a lot changes the texture and the cake loses some of that soft, tender crumb.

How to Store and Freeze Chocolate Zucchini Cake

Keep it covered at room temperature for 2 to 3 days, or in the fridge for up to 5 days.

Can You Freeze Chocolate Zucchini Cake?

Yes, and it freezes beautifully. I usually frost half the cake and freeze the other half unfrosted, with the frosting in its own container. Wrap the cake tight and freeze for up to 3 months, then thaw both and frost. If you warm a frosted slice in the microwave, the frosting sinks into the cake a little, so just add a fresh swipe on top.

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Chocolate Zucchini Sheet Cake with Cream Cheese Frosting

My French grandma's chocolate zucchini sheet cake, made with 2 cups of shredded zucchini and chocolate chips, baked in a 9×13 pan and topped with thick cream cheese frosting.

Prep Time20 minutes mins

Cook Time33 minutes mins

Total Time53 minutes mins

Course: Dessert

Cuisine: American

Servings: 24 pieces

Calories: 283kcal

Author: Bailey Campbell

Cook ModePrevent your screen from going to sleep

Ingredients 

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For the cake

• ½ cup milk
• 2 tbsp white vinegar
• ½ cup butter
• ½ cup olive oil
• 1 ¾ cup sugar
• 3 eggs
• 1 tsp vanilla extract
• 2 ½ cup all-purpose flour sifted
• ¼ cup cocoa sifted
• ½ tsp baking powder
• 1 tsp baking soda
• ½ tsp cinnamon
• 2 cups shredded zucchini
• 1 cup chocolate chips

For the frosting

• 4 ounces (113g) brick cream cheese, softened
• 2 tbsp butter
• ½ tsp vanilla extract
• 2 cups icing sugar

Instructions

• Preheat oven to 350F. Grease a 9×13" pan.
• In a small bowl, mix together the milk and vinegar and let sit to thicken.
• Make the cake: In a medium size bowl, cream together the butter and oil.
• Add the sugar, and eggs one at a time. Then add the vanilla and milk mixture.
• In a separate bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and cinnamon.
• Pour the dry ingredients into the wet ingredients and mix until completely combined. Then fold in the shredded zucchini and chocolate chips. Batter will be slightly thick.
• Pour batter into a 9×13" pan. Bake for 33-36 minutes or until the cake is baked through. To test for doneness, insert a toothpick into the center of the cake. If it comes out clean, it is done. Allow to cool completely in the pan set on a wire rack. The cake must be completely cool before frosting and assembling.
• Make the frosting: In a medium size bowl, cream the cream cheese and butter together using an electric mixer. Add the vanilla and icing sugar and continue blending.
• Cover the leftover cake and store at room temperature for 2-3 days or in the refrigerator for up to 5 days.

Notes

• Chocolate frosting: beat 2 tbsp cocoa powder into the frosting.
• Storage: covered at room temperature 2 to 3 days, fridge up to 5 days, freeze unfrosted up to 3 months.
• Dairy-free: vegan butter, almond milk, and vegan cream cheese all work.

Nutrition

Serving: 1piece | Calories: 283kcal | Carbohydrates: 41g | Protein: 3g | Fat: 12g | Saturated Fat: 5g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 0.2g | Cholesterol: 34mg | Sodium: 137mg | Potassium: 107mg | Fiber: 1g | Sugar: 29g | Vitamin A: 209IU | Vitamin C: 2mg | Calcium: 43mg | Iron: 1mg

The nutrition information provided is calculated based on industry-standard software and should be used as a general guide only. The information may vary depending on ingredient substitutions, cooking techniques, and individual serving sizes. It is the responsibility of the reader to ensure the accuracy and appropriateness of the nutritional information provided. Always consult a qualified healthcare provider for personalized medical or nutritional advice.

Tried this recipe?Please leave a comment on the blog or share a photo on @basicswithbails

More Chocolate and Zucchini Recipes

• Chocolate Zucchini Baked Oats, same chocolate and zucchini combo, but for breakfast
• Gluten Free Chocolate Cake, the one I make when I need it gluten-free
• Double Chocolate Sea Salt Fudge Brownies
• Healthy Chocolate Cottage Cheese Dessert Fruit Dip
• Crispy Air Fryer Zucchini Fries, for the rest of that zucchini

If you make Memere’s cake, leave a star rating and a comment below, it helps other bakers find it. Snap a photo and tag @basicswithbails on Instagram so I can see your slice.