Chocolate Zucchini Cake

Deep-dark Chocolate Zucchini Cake is extremely moist, made with buttermilk and shredded zucchini.  This chocolate cake recipe turns out perfect every time and can be baked in just about any size or shape of the pan. Iced with Hibiscus Swiss Meringue Buttercream.

Chocolate Zucchini Cake is what I love to make with the overabundance of zucchini I have in my garden this time of year.  I have grilled, stir-fried, casseroled, and sauteed zucchini almost daily this summer because I’m trying to be so healthy.  Now it’s time for chocolate cake!

Why Mix Zucchini Into a Cake?

Zucchini is nutrient-rich in vitamins and minerals.  It contains calcium, some sugars, carbohydrates, and a little protein.  Mostly zucchini contains water!  Over 90% of zucchini is water which makes the perfect addition to cake batter to create an extremely moist cake.   After baking a cake with shredded zucchini you won’t be able to find the zucchini back in the cake, nor will it taste like it.  Because most of the zucchini is water, it will disappear into the cake and be soaked up by the flour and cocoa powder. The structure of a zucchini breaks down because of the heat and literally disappears. And this is why my husband will eat chocolate zucchini cake…because he thinks it is just chocolate cake!  

How to make Chocolate Zucchini Cake

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1. Gather and measure all ingredients
2. Grate 2 cups zucchini and set aside.
3. In a large mixing bowl whisk or sift together flour, cocoa, baking soda, and salt.
4. In the bowl of an electric mixer, beat eggs and sugar until light in color.
5. With the mixer running, slowly drizzle in oil.  Beat on medium speed until completely combined with the sugar egg mixture
6. Stir in flour mixture only until combined.

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1. Stir in grated zucchini
2. With the mixer on low speed add boiling water.

1. Generously grease, flour, and line 3 8-inch baking pan with parchment paper.  A nonstick baking spray may also be used.
2. Evenly divide the cake batter between the three prepared pans
3. Bake in a preheated 350℉ oven.  Bake for 25-30 minutes or until the cake springs back when pressed or a toothpick comes out clean when inserted into the cake.
4. Allow for the cakes to cool 5 minutes in the pan then carefully tip cake pan upside down to release the cake onto a wire rack to cool.

Tip:

This little step will help you create extremely moist cakes every time.  While the cakes are still hot (YES! still hot) wrap each one in plastic wrap and place in the freezer.  I like to make my cakes ahead of time, so this tip works.  They will keep in the freezer for quite a while.  If storing for more than a few days, wrap in plastic THEN wrap in foil.  The cakes will keep for weeks.

If you want to use the cakes the same day, wrap in plastic wrap and cool in the refrigerator for a few hours.  Make sure the cakes are completely cold before icing.

Why Hibiscus Buttercream?

I wanted to create a bright, earthy icing for my chocolate zucchini cake and because I don’t like to use artificial coloring, I decided to reduce a strong hibiscus tea. The result was intense color and flavor that goes really well with my chocolate cake and fresh berry toppings.

Spread hibiscus buttercream icing between layers, on the top, and around the sides.  Top with a mixture of fresh berries and currants, if desired.  Refrigerate until ready to serve.  

Simple Hibiscus Syrup Reduction

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1. You will need 1 cup very hot water and 1/3 cup dried hibiscus flowers or loose hibiscus tea
2. Add dried flowers to hot water.  Allow steeping for 30 minutes.
3. Strain mixture pressing on the hibiscus to remove as much liquid as possible.  I reused the hibiscus to make myself a tall glass of iced hibiscus tea.😋
4. Pour liquid into a small saucepan.  Place over medium heat, bring to a boil. 
5. Continue to boil until liquid is reduced to 2 tablespoons.  It will begin to look like a thick glaze. Watch very carefully so the mixture doesn’t completely boil away.
6. Pour hibiscus reduction into a small bowl to cool completely.

HIbiscus reduction can be added to a Swiss Meringue Buttercream or any other icing recipe of your choice.  To make Swiss Meringue Buttercream check out my tutorial on how to make this incredibly smooth, velvety icing.  Strawberry Swiss Meringue Buttercream Tutorial.

Arrange top of the cake with assorted berries, currants, and grated chocolate.

5 from 3 votes

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Chocolate Zucchini Cake

Moist chocolate cake topped with a tangy bright HIbiscus reduction.

Servings 8 servings

Calories 842 kcal

Author Janet Barton

Ingredients

• 2 1/2 cups all-purpose flour
• 1/2 cup cocoa
• 2 teaspoons baking soda
• 1 teaspoon salt
• 2 eggs
• 2 cups sugar
• 1 cup light flavored olive oil
• 1/2 cup buttermilk
• 2 teaspoons vanilla
• 1/2 cup boiling water
• 2 cups grated zucchini

Hibiscus Swiss Meringue Buttercream

• 2/3 cup 150 g egg whites
• 1 1/4 cups 250 g sugar
• 1 1/2 cups 340 g butter 1 1/2 cups cut into 1 tbl. cubes or slices
• Pinch of salt
• 1/2 teaspoon vanilla
• 2 Hibiscus reduction

Instructions

Chocolate Zucchini Cake

1. Preheat oven to 350 degrees. Grease and flour three 8-inch round cake pans. Line with a parchment paper. Set aside. In a large bowl sift together flour, cocoa, baking soda, and salt. Set aside. In the bowl of a stand-up mixer beat eggs, With the mixer running, slowly add sugar and mix until light yellow in color. Slowly add olive oil, buttermilk, and vanilla. Mix until smooth and light in color. Beat in flour and cocoa mixture until smooth. Fold in grated zucchini then boiling water. Pour batter into prepared baking sheet and place in the preheated oven. Bake for 30 minutes or until cake springs back when lightly touched. Remove from oven and cool for 5 minutes. Invert cakes onto a cooling rack until completely cool OR for a moister cake immediately wrap in plastic and wrap and place right into a freezer. Can be frozen for several days, or place in a refrigerator until completely cool before using.

Hibiscus Swiss Meringue Buttercream

1. In a very clean bowl of an electric mixer, add egg whites and sugar. Place over a simmering pot of water, stirring constantly until temperature reaches 160 degrees F. Rub a small amount of the mixture between two fingers to make sure the sugar is dissolved. Remove from heat. Using the whisk attachment, beat until the mixture is a thick meringue and the bottom of the bowl is cool to the touch. The bowl must be cool before adding the butter. Replace the whisk with the paddle attachment. With the mixture on medium-low speed add butter once slice at a time until all of the butter has been incorporated. The mixture should be silky smooth and thick. The mixture may begin to look curdled, keep mixing until it is smooth. This can take 10 minutes or so. Mix in salt and vanilla.

2. Replace the whisk with the paddle attachment. With the mixture on medium-low speed add butter one slice at a time until all of the butter has been incorporated. The mixture should be silky smooth and thick. The mixture may begin to look curdled, keep mixing until it is smooth. This can take 10 minutes or so. Mix in salt and vanilla. Add hibiscus reduction and keep mixing until the mixture is silky again.

Recipe Notes

Recipe Notes
Chocolate Zucchini Cake batter can be baked in a 9 x 13-pan, 12 x 17-inch sheet pan, two 9-inch round cake pans as well.
This little step will help you create extremely moist cakes every time. While the cakes are still hot (YES! still hot) wrap each one in plastic wrap and place in the freezer. I like to make my cakes ahead of time, so this tip works. They will keep in the freezer for quite a while. If storing for more than a few days, wrap in plastic THEN wrap in foil. The cakes will keep for weeks.

If you want to use the cakes the same day, wrap in plastic wrap and cool in the refrigerator for a few hours. Make sure the cakes are completely cold before icing.

Buttercream can be made in advance and stored in the refrigerator for 3-4 days or frozen for several weeks. Thaw frozen buttercream overnight in the refrigerator. Bring to room temperature then beat until creamy.
If the buttercream happens to have a curdled look to it, that means it is too cold. Take a warm washcloth and place it on the bottom of the mixing bowl while beating. Continue this process just until the mixture is silky smooth. Not melt the butter!

Nutrition Facts

Chocolate Zucchini Cake

Amount Per Serving (1 slice)

Calories 842 Calories from Fat 360

% Daily Value*

Fat 40g62%

Saturated Fat 23g115%

Cholesterol 134mg45%

Sodium 939mg39%

Potassium 283mg8%

Carbohydrates 116g39%

Fiber 3g12%

Sugar 83g92%

Protein 10g20%

Vitamin A 1210IU24%

Vitamin C 6mg7%

Calcium 53mg5%

Iron 3mg17%

* Percent Daily Values are based on a 2000 calorie diet.

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