Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.

In a medium bowl, whisk together flour, baking soda, cinnamon, nutmeg, and salt.

In a large mixing bowl, combine granulated sugar, brown sugar, and vegetable oil. Mix well.

Beat in eggs and vanilla extract until smooth.

Gradually add the dry ingredients to the wet ingredients, stirring until just combined.

Fold in the shredded zucchini gently.

Pour the batter into the prepared baking dish and spread evenly.

Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.

Allow the bars to cool completely before frosting.

Beat cream cheese and butter together until fluffy.

Gradually add powdered sugar, mixing well after each addition.

Stir in vanilla extract and spread evenly over the cooled zucchini bars.