You will never guess what's in this beaut of a chocolate cake

Note: The above video is a different recipe, but another example of incorporating sweet potato in a chocolate treat.

Tra-la-la, it's The Fall Cookbook Cake Parade: a new cake from a new cookbook every single day. Are your costumes cake pans ready?

Today: A chocolate cake with (delicious, vegetal) secrets from Better Baking.

School-Party Sheet Cake
School-Party Sheet Cake

School-Party Sheet Cake by Genevieve Ko

Would you just look at this chocolate cake! The swoop! The swirl! You might just want to lie down in that frosting. Would you still want to do so if I told you it was not a buttercream, but a brilliant combination of dark chocolate and—seriously—sweet potato purée? Watch how it's made here:

Genevieve Ko, whose book Better Baking includes this recipe, doesn't believe in sneaking in vegetables. So she'd want me to tell you. She'd also want me to tell you that there's zucchini in the cake, too. For a cake that might seem secretive, it's not sneaky:

When I bring treats to my girls' school parties, I don't want them to be mortified by their mom's weird food—nor do I want to turn their classmates into hyperactive rascals with empty calories. That means something that looks familiar but tastes better than the original. Enter this easy sheet cake. Zucchini keeps the cocoa–chocolate chip cake extra moist, and sweet potato swirls into a frosting as creamy as that canned stuff, with far more flavor (and no added sugar). Dark chocolate—semisweet or a lower-percentage bittersweet—makes the cake luxurious and sophisticated enough for adults. Kids may ask about the bits of green zucchini in the cake. I'm not a believer in sneaking in veggies, so I tell them. Even if they balk, they still gobble up the cake once they take a bite or hear their friends raving. Party on!

See? Not a secret. Now, go tell everyone you know.

School-Party Sheet Cake

By Genevieve Ko

For the chocolate-zucchini cake

1 pound (453g) zucchini (about 4 small), trimmed

2 1/2 cups (360g) white whole wheat flour

1/2 cup (48g) unsweetened cocoa powder

1 teaspoon ground cinnamon

1 teaspoon baking soda

1/2 teaspoon baking powder

1/2 teaspoon salt

1 1/2 cups (312g) sugar

1 cup (245g) buttermilk, at room temperature

1/2 cup (112g) grapeseed or other neutral oil 3 large eggs, at room temperature

1 teaspoon pure vanilla extract

1 cup (180g) semisweet chocolate chips

For the sweet potato frosting

1 (15-ounce; 425-g) can pure sweet potato puree

10 ounces (283 g) semisweet or bittersweet chocolate, finely chopped (1⅔ cups)

View Full Recipe

Recipe gratefully reprinted from Better Baking.

RELATED: 6 foods to smother in chocolate

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