Chocolate Swirl Zucchini Sheet Cake

INGREDIENTS

• 3 cups all-purpose flour
• 1/2 cup unsweetened cocoa powder
• 2 teaspoons baking soda
• 1 teaspoon salt
• 3 cups white sugar
• 1 1/2 cups canola oil
• 3 eggs
• 3 cups grated zucchini
• 1 teaspoon vanilla extract
• 1 cup buttermilk
•  
• 1 (8 ounce) package cream cheese, softened
• 1/4 cup white sugar
• 1 egg
• 1/2 cup milk chocolate chips
• 1/2 cup semisweet chocolate chips