Whole Wheat Zucchini Cake with Basil Buttercream

Recipe Intro From thefeedfeed

Photo by @andrealoretdemola

One of my biggest character flaws is I don’t love cake, or I guess more specifically, I hate frosting. My birthday is the 3rd of July, so every year (all 36 of them!) I have a very basic flag cake topped with whipped cream and fresh berries, my ideal kind of dessert. At my wedding, we skipped overpriced wedding cake for an ice cream sundae bar (highly recommended) and don’t get me started on cupcakes. Suffice to say, if I’m going to make a cake, it most definitely is not going to be topped with American buttercream.  

As for baking cakes? I can’t get enough and my search for a palatable buttercream has been an ongoing affair.  I’ve forayed into swiss meringue buttercream, but it's a fickle beast.  I love that it's not overly sweet, but working with a meringue is never stress free.  And CAKE. SHOULD. BE. FUN! 

Enter German Buttercream. German Buttercream, in my opinion, is in a league of its own when it comes to topping a cake.  It’s fairly fool proof, it's not overly sweet, it’s pretty stable, and you can easily infuse it with your favorite flavors. Now before I lose you, I promise, this recipe is easy.  If you can make pudding you can make this buttercream!  A few bits of advice; you want the butter to be room temperature, like really room temperature.  Don’t rush it. I am the queen of softening butter at 5 second intervals in the microwave when I want to make cookies STAT, but this just won’t cut it here. Also, make sure that your pastry cream has had a chance to chill, and therefore, set.  This will help to ensure the resulting buttercream is nice and stable. If things start to go array, fear not.  Pop everything in the fridge to chill for a few minutes, then just start whipping. Like most things in life,  eventually it will all come together!

Now that we have thoroughly covered the frosting, let’s not forget about the cake! This whole wheat based zucchini cake is perfectly spiced, not overly sweet, and is oil based so it stays nice and moist. Plus, it mixes up easily with just two bowls so it balances out the bougie buttercream. 

Playing off the mellow sweetness, I decided to infuse the buttercream with fresh basil which works in harmony with the slightly spicy and vegetal flavor of the cake, but feel free to skip that if you’d rather go the vanilla route.  Whatever you do, promise me you’ll ditch the classic buttercream and give this recipe a try soon!


Recipe and Headnote Molly Adams

*It’s important to let this mixture come to a boil to ensure you achieve the desired texture.  You do not want a rolling boil, just a few bubbles need to form in the center of the saucepan.


Prep time 3hrs
Cook time 30mins
Serves or Makes: 10


For the Zucchini Cake

  • Nonstick cooking spray, as needed
  • 2 cups whole wheat flour
  • 1 tablespoon ground cinnamon
  • 2 teaspoons baking powder
  • 1 teaspoon ground ginger
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1/4 teaspoon ground nutmeg
  • 1 3/4 cups sugar
  • 4 eggs
  • 1 1/2 cups vegetable oil
  • 2 teaspoons vanilla extract
  • 1/2 cup unsweetened applesauce
  • 3 cups packed grated zucchini (from 2 medium zucchini)
  • 1 cup unsweetened shredded coconut

For the Basil Buttercream

  • 2 cups packed basil leaves
  • 1 cup whole milk
  • 1/2 cup sugar
  • 4 egg yolks
  • 2 tablespoons cornstarch
  • 1 tablespoon vanilla extract
  • Pinch salt
  • 2 sticks unsalted butter, at room temperature

To Assemble

  • Chopped pistachios, optional, for garnish
  • Unsweetened shredded coconut, optional, for garnish
  • Edible flowers, optional, for garnish


  • Step 1

    Preheat the oven to 350˚F and line two 9-inch cake pans with parchment paper, then spray with nonstick cooking spray.

  • Step 2

    In a medium bowl, whisk together the flour, baking powder, spices, baking soda and salt. In a separate large bowl, whisk together the sugar, eggs, oil, vanilla and applesauce. Add zucchini to the wet ingredients, folding to combine. Sprinkle dry ingredients on top of the wet ingredients, and fold to combine until no streaks of flour remain.

  • Step 3

    Add coconut, folding until incorporated. Divide the batter evenly between prepared pans, then bake for 30-35 minutes or until a cake tester inserted into the middle of the cake comes out clean.

  • Step 4

    Remove cakes from the oven and let cool for 15 minutes in the pan, then invert onto a wire cooling rack to cool completely.

  • Step 5

    While the cake is cooling, make the basil buttercream. Add basil and milk to a small saucepan and bring to just a simmer over medium low heat. When you see the milk just beginning to simmer, remove from heat. Cover and let infuse for about 30 minutes.

  • Step 6

    Add sugar, egg yolks, cornstarch, vanilla extract and salt to a medium heatproof bowl. Whisk until well combined. Set aside.

  • Step 7

    Once the milk has infused, strain the milk through a fine mesh strainer into a medium bowl, or another saucepan. Discard basil, extracting as much milk from the basil leaves as possible.

  • Step 8

    Bring milk back to just a simmer over medium-low heat, then slowly ladle about ⅓ cup warm milk into the egg yolk mixture, whisking constantly until smooth. Add the egg and milk mixture back to the saucepan and cook over medium-low heat, stirring constantly, until the mixture starts to thicken and just reaches a boil, about 3-4 minutes.* Strain the basil-infused pastry cream through a fine mesh sieve into a clean bowl, which will remove any lumps or bits of overcooked egg, then cover the surface of pastry cream with plastic wrap or beeswax wrap and place in the refrigerator to cool for at least one hour, or up to overnight.

  • Step 9

    Once pastry cream has chilled, add softened butter to the bowl of a stand mixer fitted with the paddle attachment and cream until light and fluffy, about 3-4 minutes. Add the chilled pastry cream to the bowl 1 tablespoon at a time and mix at medium-high speed until the mixture is smooth, light and fluffy. Repeat until all of the pastry cream has been added. If the mixture appears broken at all, just keep mixing until it transforms into a light and fluffy frosting.

  • Step 10

    To assemble, add one layer of cooled cake to a cake plate or stand. Add half of the buttercream, then top with the remaining cake layer. Add remaining buttercream to the top of the cake and smooth into an even layer.

  • Step 11

    Top with chopped pistachios, shredded coconut, and edible flowers, if desired, before serving.