Preheat the oven to 350 degrees F. Spray a 9x13 baking pan with nonstick baking spray.
Add the 1/2 cup vegetable oil, 1 cup granulated sugar, 1/2 cup light brown sugar, 2 large eggs, and 2 teaspoons vanilla extract to a bowl. Beat until the eggs are incorporated.
Add in the 3 cups zucchini and stir to combine.
In a separate large bowl, add in the 2 cups all-purpose flour, 3 teaspoons ground cinnamon, 1/4 teaspoon ground nutmeg, 1/2 teaspoon baking soda, 2 teaspoons baking powder, and 1 teaspoon salt. Whisk until incorporated.
Pour the wet mixture into the dry and beat until all of the flour is incorporated.
Stir in the 1 cup nuts or chocolate chips, if you’re using them.
Pour the batter into the prepared baking pan.
Place in the oven and bake for 40 to 45 minutes or until a toothpick inserted into the center of the cake comes out clean.
Remove from the oven and let cool completely.
Once cooled, frost with the cream cheese frosting.
Frosting
In a large bowl, add in the 8 ounces cream cheese and 1 cup butter. Beat with a hand mixer on medium until smooth and creamy.
Add in the 3 cups powdered sugar, 1 teaspoon vanilla extract, and 1 tablespoon whole milk. Beat on low until most of the powdered sugar is worked into the frosting.
Turn the mixer to medium and continue to beat until the frosting is smooth.
Spread the frosting on the cooled cake using an offset spatula.
Dust the top with about 1/8 teaspoon ground cinnamon using a very small sifter.
Cut and serve.
Cover with plastic wrap and store in the refrigerator.
Notes
Storage: Store covered or in an airtight container in the refrigerator for up to 5 days.