Step 1
Preheat oven to 350 F. Line a 9x13-inch baking pan with parchment paper and set aside.
Step 2
In a large bowl, whisk together flour, cocoa powder, baking soda, baking powder and salt. Set aside.
Step 3
In a separate large bowl, beat together C&H® Granulated Sugar, C&H® Light Brown Sugar, vegetable oil, melted butter, sour cream and vanilla. Mix on medium-high speed until well combined, about 2 minutes. Add eggs and mix until combined, about 1 minute.
Step 4
Pour wet ingredients into the bowl of dry ingredients. Use a rubber spatula to mix just until combined (avoid over mixing). Add shredded zucchini and chocolate chips. Stir just until incorporated.
Step 5
Transfer batter to prepared pan and spread batter evenly. Bake at 350 F for 30 to 35 minutes or until a toothpick inserted in the center comes out with little to no crumbs. Allow cake to cool completely in the pan.
Step 6
For the frosting, beat butter with an electric mixer until light and fluffy, about 2 minutes. Add C&H® Powdered Sugar and cocoa powder and mix until combined. Add vanilla and milk, one tablespoon at a time, and mix until frosting is smooth.
Step 7
Transfer frosting to cooled cake and use an offset spatula to spread evenly. Cut cake and serve.
For the zucchini, pat until slightly dry. The squash should still have a little moisture in it when adding it to the cake batter. Store cake in an airtight container at room temperature for up to 3 days.