Decadent Chocolate Zucchini Banana Cake with Vanilla Coffee Frosting

I love finding ways to sneak vegetables into desserts. My kids have no idea they’re eating zucchini when I serve this cake, and honestly, that makes me feel like I’m winning at parenting. The zucchini keeps everything moist without adding any weird flavors. Plus, it’s a great way to use up all that zucchini from the garden that seems to multiply overnight.

This cake combines chocolate, banana, and zucchini in a way that just works. The banana adds natural sweetness, and the chocolate makes everyone forget they’re eating something with vegetables in it. Then I top it with vanilla coffee frosting because, let’s be real, everything is better with coffee flavor.

The best part? You can make this when your bananas are getting too ripe for eating but perfect for baking. It’s like giving your produce a second chance while creating something everyone will actually want to eat.

What Kind of Zucchini Should I Use?

For this cake, you’ll want to use small to medium-sized zucchini since they tend to be more tender and have fewer seeds than the larger ones. The skin is totally fine to leave on – it actually adds nice flecks of color and extra nutrients to your cake. When picking zucchini at the store, look for ones that feel firm and heavy for their size, with smooth, unblemished skin. After grating, make sure to squeeze out as much water as possible using a clean kitchen towel or paper towels, since too much moisture can make your cake soggy. If you only have large zucchini on hand, just scoop out the seeds before grating and you’ll be good to go.

Options for Substitutions

This cake is surprisingly adaptable – here are some swaps you can make without compromising the final result:

• Zucchini: Yellow squash works just as well as zucchini in this recipe. You can also try finely grated carrots, though the texture will be slightly different. Make sure to squeeze out excess moisture no matter which veggie you choose.
• Coconut oil: Melted butter, vegetable oil, or even applesauce can replace the coconut oil. If using applesauce, use 1/3 cup and expect a slightly denser cake.
• Honey: Maple syrup or agave nectar work perfectly here. You can also use 1/2 cup granulated sugar mixed with 2 tablespoons of water if that’s what you have on hand.
• All-purpose flour: For a gluten-free version, use a 1:1 gluten-free flour blend. Whole wheat flour can substitute half the all-purpose flour for a nuttier flavor.
• Chocolate chunks: Mini chocolate chips, chopped dark chocolate, or even butterscotch chips can replace the chocolate chunks. Nuts like walnuts or pecans also work great.
• Instant coffee powder: If you don’t have instant coffee, use 2 tablespoons of strong brewed coffee (reduce other liquids slightly) or simply omit it for a plain vanilla frosting.

Watch Out for These Mistakes While Baking

The biggest mistake when making this cake is skipping the crucial step of squeezing out excess water from the grated zucchini – use a clean kitchen towel or paper towels to press out as much moisture as possible, or your cake will turn out dense and soggy.

Make sure your bananas are truly ripe with brown spots, as underripe bananas won’t mash properly and can create lumps in your batter, while overripe bananas add the perfect sweetness and moisture.

For the frosting, ensure your cream cheese and butter are completely at room temperature before mixing – cold ingredients will create a lumpy frosting that won’t spread smoothly, and dissolve the instant coffee powder in a teaspoon of warm water first to prevent grainy texture.

Don’t overmix the batter once you add the flour, as this can make your cake tough, and fold in the chocolate chunks gently at the very end to prevent them from sinking to the bottom.

What to Serve With Chocolate Zucchini Banana Cake?

This cake is perfect on its own, but I love serving it with a hot cup of coffee or tea since the vanilla coffee frosting pairs so well with warm drinks. For special occasions, try adding a scoop of vanilla ice cream or a dollop of whipped cream on the side – the cool creaminess really complements the rich chocolate and spiced cake. If you want to make it feel more like dessert, fresh berries like strawberries or raspberries add a nice tart contrast to all that sweetness. This cake also makes a great afternoon snack with just a cold glass of milk for dunking!

Storage Instructions

Keep Fresh: This chocolate zucchini banana cake stays moist and delicious when covered tightly and stored at room temperature for up to 3 days. If you’ve added the vanilla coffee frosting, it’s best to keep it in the refrigerator in an airtight container for up to 5 days – just bring it back to room temperature before serving for the best flavor.

Freeze: You can freeze this cake for up to 3 months, either frosted or unfrosted. I like to wrap individual slices in plastic wrap and then place them in a freezer bag for easy grab-and-go treats. If freezing the whole cake, wrap it tightly in plastic wrap and then aluminum foil.

Serve: Frozen cake slices thaw beautifully at room temperature in about 30-45 minutes. If you froze it without the frosting, you can always whip up a fresh batch of that vanilla coffee frosting when you’re ready to serve. The cake actually tastes even better the next day as all those flavors meld together!

Estimated Nutrition

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

• Calories: 3200-3500
• Protein: 32-38 g
• Fat: 170-190 g
• Carbohydrates: 420-450 g

Ingredients

For the cake:

• 2 small zucchini (about 1 1/2 cups, grated and drained)
• 2 medium bananas (about 3/4 cup mashed)
• 1/2 cup melted coconut oil
• 1/3 cup honey
• 2 eggs
• 2 tsp vanilla extract
• 1 1/2 cups all-purpose flour
• 1 1/2 tsp baking soda
• 1 tsp ground cinnamon (optional)
• 1/2 tsp kosher salt
• 1 cup semi-sweet or dark chocolate chunks

For the frosting:

• 4 oz cream cheese, softened
• 1/2 cup salted butter, softened
• 1 1/2 cups confectioners’ sugar
• 1 tbsp instant coffee powder
• 2 tsp vanilla extract

Step 1: Prepare the Baking Pan and Oven

Preheat your oven to 350° F.

Line an 8-inch square baking pan with parchment paper, ensuring it covers the bottom and sides for easy removal later.

Step 2: Prep the Zucchini

• 2 small zucchini (about 1 1/2 cups, grated and drained)

Place the grated zucchini into a clean kitchen towel.

Gather the towel around the zucchini and squeeze out as much excess water as possible.

Removing the extra moisture is crucial to ensure the bread doesn’t turn out soggy.

Step 3: Make the Banana Zucchini Bread Batter

• 2 medium bananas (about 3/4 cup mashed)
• 1/2 cup melted coconut oil
• 1/3 cup honey
• 2 eggs
• 2 tsp vanilla extract
• 1 1/2 cups all-purpose flour
• 1 1/2 tsp baking soda
• 1 tsp ground cinnamon (optional)
• 1/2 tsp kosher salt
• zucchini (drained from Step 2)
• 1 cup semi-sweet or dark chocolate chunks

In a large mixing bowl, combine the mashed bananas, melted coconut oil, honey, eggs, and vanilla extract.

Stir until the mixture is smooth.

Add the all-purpose flour, baking soda, ground cinnamon (if using), and kosher salt, and gently mix until just combined, being careful not to over-mix.

Fold in the drained zucchini from Step 2 and the chocolate chunks until evenly distributed throughout the batter.

I like to use dark chocolate chunks for a richer flavor, but semi-sweet works well too.

Step 4: Bake the Bread

• banana zucchini bread batter from Step 3

Pour the prepared batter into the lined baking pan from Step 1.

Use a spatula to smooth the top.

Bake in the preheated oven for 30-40 minutes, or until the center is just set and a toothpick inserted into the center comes out mostly clean.

Allow the bread to cool in the pan for at least 30 minutes before adding the frosting.

Step 5: Make the Coffee Cream Cheese Frosting

• 4 oz cream cheese, softened
• 1/2 cup salted butter, softened
• 1 1/2 cups confectioners’ sugar
• 1 tbsp instant coffee powder
• 2 tsp vanilla extract

In a small bowl, dissolve the instant coffee powder in 1 tablespoon of hot water.

In the bowl of a stand mixer, beat together the softened cream cheese and softened butter until light and fluffy, about 2 minutes.

Add the confectioners’ sugar, dissolved coffee, and vanilla extract, then beat for another 2 to 4 minutes until the frosting is fluffy and smooth.

For even more coffee flavor, I sometimes add an extra half teaspoon of instant coffee powder to the mix.

Step 6: Frost and Serve

• banana zucchini bread (baked and cooled from Step 4)
• coffee cream cheese frosting from Step 5

Carefully remove the cooled banana zucchini bread from the pan and place it on a serving platter.

Spread the fluffy coffee cream cheese frosting evenly over the top.

Slice the bread into squares, serve, and enjoy.

Decadent Chocolate Zucchini Banana Cake with Vanilla Coffee Frosting

Delicious Decadent Chocolate Zucchini Banana Cake with Vanilla Coffee Frosting recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 17 minutes mins

Cook Time 35 minutes mins

Total Time 52 minutes mins

Servings 4

Calories 3350 kcal

Ingredients

  

For the cake:

• 2 small zucchini (about 1 1/2 cups, grated and drained)
• 2 medium bananas (about 3/4 cup mashed)
• 1/2 cup melted coconut oil
• 1/3 cup honey
• 2 eggs
• 2 tsp vanilla extract
• 1 1/2 cups all-purpose flour
• 1 1/2 tsp baking soda
• 1 tsp ground cinnamon (optional)
• 1/2 tsp kosher salt
• 1 cup semi-sweet or dark chocolate chunks

For the frosting:

• 4 oz cream cheese, softened
• 1/2 cup salted butter, softened
• 1 1/2 cups confectioners’ sugar
• 1 tbsp instant coffee powder
• 2 tsp vanilla extract

Instructions

 

• Preheat your oven to 350° F. Line an 8-inch square baking pan with parchment paper, ensuring it covers the bottom and sides for easy removal later.
• Place the grated zucchini into a clean kitchen towel. Gather the towel around the zucchini and squeeze out as much excess water as possible. Removing the extra moisture is crucial to ensure the bread doesn’t turn out soggy.
• In a large mixing bowl, combine the mashed bananas, melted coconut oil, honey, eggs, and vanilla extract. Stir until the mixture is smooth. Add the all-purpose flour, baking soda, ground cinnamon (if using), and kosher salt, and gently mix until just combined, being careful not to over-mix. Fold in the drained zucchini from Step 2 and the chocolate chunks until evenly distributed throughout the batter. I like to use dark chocolate chunks for a richer flavor, but semi-sweet works well too.
• Pour the prepared batter into the lined baking pan from Step 1. Use a spatula to smooth the top. Bake in the preheated oven for 30-40 minutes, or until the center is just set and a toothpick inserted into the center comes out mostly clean. Allow the bread to cool in the pan for at least 30 minutes before adding the frosting.
• In a small bowl, dissolve the instant coffee powder in 1 tablespoon of hot water. In the bowl of a stand mixer, beat together the softened cream cheese and softened butter until light and fluffy, about 2 minutes. Add the confectioners’ sugar, dissolved coffee, and vanilla extract, then beat for another 2 to 4 minutes until the frosting is fluffy and smooth. For even more coffee flavor, I sometimes add an extra half teaspoon of instant coffee powder to the mix.
• Carefully remove the cooled banana zucchini bread from the pan and place it on a serving platter. Spread the fluffy coffee cream cheese frosting evenly over the top. Slice the bread into squares, serve, and enjoy.