Preheat oven to 350℉. Either spray or line a 10x15 baking pan with parchment paper. *If making a double batch use a 13x18 pan. Grate your zucchini and set aside.
In a mixing bowl whisk together brown sugar, butter, eggs, sour cream, and vanilla extract until well combined. Then add in zucchini and mix until well combined.
In a separate mixing bowl add your flour, baking powder, cinnamon, and salt. Mix until combined.
Next add the dry mixture to the wet mixture and mix until combined and there are no dry spots. Don't overmix.
Pour the batter into prepared baking sheet and bake for 27-30 minutes or until golden and the middle is set and not jiggly. This may vary with ovens. For a 13x18 pan bake approx. 33-35 minutes. For frosting cream the cream cheese and butter together in a stand mixer or with a hand mixer. Slowly add the powdered sugar, mixing well after each addition. Add vanilla extract and mix until smooth.
Remove baking sheet and set on a cooling rack. Cool completely before frosting.
