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!

Preparation Time	15-20 minutes
Cooking Time	30-40 minutes
Total Time	45-60 minutes
Level of Difficulty	Medium

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:

• 1 1/2 cups all-purpose flour (I use King Arthur)
• 1 tsp ground cinnamon (optional, enhances chocolate flavor)
• 2 medium bananas (about 3/4 cup mashed, ripe with brown spots)
• 1/3 cup honey
• 1 1/2 tsp baking soda
• 1/2 cup melted coconut oil (cooled slightly before mixing)
• 2 eggs (room temperature)
• 2 tsp vanilla extract (I use Madagascar vanilla)
• 1/2 tsp kosher salt
• 2 small zucchini (about 1 1/2 cups grated and drained)
• 1 cup semi-sweet chocolate chunks (or chopped dark chocolate, 60% cacao)

For the frosting:

• 4 oz cream cheese (softened to room temperature)
• 1 tbsp instant coffee powder (freshly opened for best flavor)
• 2 tsp vanilla extract
• 1/2 cup salted butter (softened, I prefer Kerrygold)
• 1 1/2 cups confectioners’ sugar (sifted to remove lumps)

Step 1: Prepare Ingredients and Oven Setup

• 2 small zucchini
• 2 medium bananas

Preheat your oven to 350°F and line an 8-inch cake pan with parchment paper.

While the oven heats, grate the zucchini and place it in a fine-mesh strainer or clean kitchen towel, then squeeze out as much water as possible—this is crucial to prevent a soggy cake.

Mash the ripe bananas in a large bowl until mostly smooth with a few small lumps remaining.

Set both the zucchini and bananas aside.

I like to let my eggs and cream cheese sit out for at least 30 minutes before baking, as they incorporate more smoothly into batters and frostings when at room temperature.

Step 2: Create the Wet Batter Base

• 2 medium bananas
• 1/2 cup melted coconut oil
• 1/3 cup honey
• 2 eggs
• 2 tsp vanilla extract

In a large mixing bowl, combine the mashed bananas with the cooled melted coconut oil, honey, room-temperature eggs, and vanilla extract.

Whisk these ingredients together until well combined and relatively smooth, about 1 minute.

The mixture should be homogeneous and ready to receive the dry ingredients.

This careful mixing of wet ingredients first ensures even distribution of moisture throughout the batter.

Step 3: Combine Dry Ingredients and Fold Into Batter

• wet ingredient mixture from Step 2
• 1 1/2 cups all-purpose flour
• 1 1/2 tsp baking soda
• 1 tsp ground cinnamon
• 1/2 tsp kosher salt
• drained zucchini from Step 1
• 1 cup semi-sweet chocolate chunks

In a separate medium bowl, whisk together the all-purpose flour, baking soda, cinnamon (if using), and kosher salt.

Add this dry mixture to the wet batter from Step 2 and fold gently with a spatula until just combined—don’t overmix, as this will develop gluten and create a tough crumb.

Once no flour streaks remain, fold in the drained zucchini from Step 1, then gently fold in the chocolate chunks until evenly distributed throughout.

Pour the batter into your prepared pan and smooth the top slightly.

Step 4: Bake the Cake

Place the cake pan in the preheated 350°F oven and bake for 30–40 minutes, until a toothpick inserted into the center comes out clean or with just a few moist crumbs.

The cake should be set around the edges but may have slight jiggle in the very center when you gently shake the pan.

Remove from the oven and let cool in the pan for 30 minutes before turning out onto a wire rack to cool completely.

I prefer to frost this cake at room temperature rather than when it’s still warm, as the frosting sets more neatly.

Step 5: Prepare the Vanilla Coffee Frosting

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

While the cake cools, beat the softened cream cheese and salted butter together in a clean mixing bowl using an electric mixer on medium-high speed for about 2 minutes, until light, fluffy, and pale.

Dissolve the instant coffee powder in 2 tablespoons of hot water (or use hot brewed coffee for deeper flavor) and let it cool slightly, about 2 minutes.

Add the sifted confectioners’ sugar, the cooled coffee mixture, and vanilla extract to the butter mixture and beat for 2–4 minutes until smooth, fluffy, and spreadable.

If the frosting seems too soft, refrigerate it for 10–15 minutes before frosting the cake.

Step 6: Frost and Serve

• cooled cake from Step 4
• vanilla coffee frosting from Step 5

Once the cooled cake from Step 4 is completely cool, spread or crumb-coat the frosting from Step 5 evenly over the top and sides using an offset spatula or butter knife.

For a rustic look, you can leave the frosting textured, or smooth it out for a more polished finish.

Slice into portions and serve immediately, or refrigerate for up to 2 days if making ahead.

The combination of chocolate, banana, and zucchini becomes even more cohesive after a day, as the flavors continue to meld.