School Party Sheet Cake Recipe
Chocolate Zucchini Cake
- Nonstick cooking spray
- 1 pound (about 4 small) zucchini, trimmed
- 2½ cups white whole wheat flour
- ½ cup unsweetened cocoa powder
- 1 tsp. cinnamon
- 1 tsp. baking soda
- 1 tsp. baking powder
- ½ tsp. salt
- 1½ cups sugar
- 1 cup buttermilk, at room temperature
- ½ cup grapeseed or other neutral oil
- 3 large eggs, at room temperature
- 1 tsp. pure vanilla extract
- 1 cup semisweet chocolate chips
- 1 (15-ounce) can pure sweet potato puree
- 10 ounces semisweet or bittersweet chocolate (55 to 60 percent cacao), finely chopped (1 ⅔ cups)
Sweet Potato Frosting
Active time: 35 minutes
Total time: 1 hour 30 minutes
To make cake: Position a rack in the center of oven and preheat to 325°. Coat a 9"x 13" cake pan or dish with cooking spray. If using a metal pan, line bottom and sides with foil or parchment paper and spray again.
Set a box grater on paper towels and grate zucchini on large holes. Spread grated zucchini on paper towels, top with more paper towels, and press gently to remove excess moisture.
In a large bowl, sift flour, cocoa powder, cinnamon, baking soda, baking powder, and salt. In a medium bowl, whisk sugar, buttermilk, oil, eggs, and vanilla until very smooth. Make a well in dry ingredients and pour in wet ingredients. Whisk, gradually drawing in dry ingredients, until smooth. Using a silicone spatula, fold in zucchini and chocolate chips until evenly incorporated. Spread batter in an even layer in prepared pan.
Bake cake until a toothpick inserted in the center comes out clean and cake top springs back slightly when pressed with a fingertip, 45 to 50 minutes. Let cool completely in pan on a rack.
Meanwhile, make frosting: In a large saucepan, bring sweet potato puree to a simmer over medium heat, stirring frequently. Remove from heat and add chocolate. Stir until smooth. Cool, stirring occasionally, until mixture is at room temperature; it should form soft peaks but not be stiff. Spread frosting over cooled cake. Serve immediately or store in refrigerator, covered, up to 3 days.